[SOLVED] Connection disappears for short periods without any pattern on 3 routers.

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Routers - Zyxel Keenetic Lite 2, Tenda AC8
Modem - BDCOM P1501DT

PC specs:
Mobo: Gigabyte B550 Aorus Elite
PCU: Seasonic Prime GX-750
Windows 10 Pro
if something else is required - I can send it too.

ISP may not prove anything useful since I'm not in the US, I'm from Ukraine. Connection type - Optical, up to 100 Mbps. Only 3 devices connected to the router, and only 1 (PC) is using the connection non-stop. Absolutely no error messages from the ISP or Windows.

Now let's get to the problem. Was using my main router - Zyxel Keenetic Lite 2 for about 4 years now, and for the last couple of weeks, the connection was disappearing for short 30 second periods, without any logic. It could be once in two hours, and it could be every 5-10 minutes. Intervals were always different, and this is why it was quite hard to get all of the information about the problem. I've downloaded the StarTrinity CST software to track the exact connection times, but it didn't give me hardly any other information. Also, it is a must to mention that the connection disappears on the other devices like the TV, so the problem is most likely not in the PC but on the way from the ISP to the router.

After contacting my ISP, the technician came and changed my modem to the one mentioned above, but it didn't solve the problem. He suggested changing the router itself. After some time I've tried connecting my PC directly from the modem, without the router, and there were no problems with the internet connection for about 5 hours, so I've figured that the problem is in the router itself. After buying Tenda AC8 that my friend suggested, I've noticed that a similar issue appeared - the internet disappears without any reason, and now not for 30 seconds, but for an unlimited period unless I restart the router manually or Windows Diagnostics restarts it from the PC's end (I'm not sure how this works, but it seems like it).

I'm having really mixed feelings about this problem since it is really hard to trace the problem. I think that it may be the faulty router, and I wanted to try to return it and buy another one, but what if the problem is not with the router, but with the actual connection, and those routers simply react to connection drop differently (the first one resets itself after 30 seconds, the second one doesn't)?

Hope to get some useful info on how to trace the issue properly and what steps to take to fix everything. If you need any other bit of information - please, ask, I will be glad to send it.

Thank you, happy new year, and stay safe!
 
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Just an update, on the 12th of January an official Realtek LAN Driver [1‎0.046.1231.2020] was released (can be downloaded on your MB official website) that supposedly fixed the problem, and for a week I haven't encountered it.

Wanted to say thank you to everyone who tried to help, even when the issue was this much not obvious lol.
 
Your best test is to leave constant ping to the router IP and to the first ISP router IP. You can find the ISP router by running tracert to 8.8.8.8, it should be hop 2 in most cases.

If you see packet loss to the router IP the problem is either your PC or the router. If this is ok but you see loss to the ISP router it is much more likely it is some problem with the internet connection itself. Does the modem box have any logs or diagnostic messages that might give you a clue.
 

Mr.Spock

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go to Powershell and run the command ipconfig /all - might be a setting on the router which affects your DHCP lease times.

one solution might be to attach a timer switch to the router and set it to restart nightly while you're sleeping...
 
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It sounds like there's something wrong with the system you're using. You have something else that you can test wired?

If not, boot a linux live cd and see if you have any issues under the live environment.
Yes, our TV tuner is connected via a wired connection too, and as I mentioned, the internet disappears on the TV at the same time as on the PC, so the problem is not with the router->PC connection, more likely with the router/s itself/themselves, or with the modem-ISP part.

Your best test is to leave constant ping to the router IP and to the first ISP router IP. You can find the ISP router by running tracert to 8.8.8.8, it should be hop 2 in most cases.

If you see packet loss to the router IP the problem is either your PC or the router. If this is ok but you see loss to the ISP router it is much more likely it is some problem with the internet connection itself. Does the modem box have any logs or diagnostic messages that might give you a clue.
So I've started the constant ping to the router, the second IP, which is my personal/ISP router IP, and the third one in the list, just in case. When the connection dropped - the ping didn't even reach my router. There were no data in the router log about it whatsoever. This time I was using the Zyxel router, but with the Tenda router the issue was basically the same (I will test it too), I couldn't access the router via its usual address 198.168.0.1.

It could seem like the problem is with the system-router setup, but then why the connection drops on the TV and other devices, even the ones that were connected via WiFi? Is it possible that there are some power issues, so the router gets rebooted or something?

update:
I've tried rebooting the Zyxel router manually through cmd-telnet, and the time it takes to reboot it is ~35 seconds, which is really close to the timeframe of my internet shortages, I could guess that with the Zyxel router the internet disappears because it keeps restarting, but Tenda router doesn't restart itself?
 
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Are you actually using both routers in the path at the same time.

If you are swapping them and only running 1 at a time it is very strange. A router could be defective in some way but for 2 routers of different brands to be defective in the same way would be extremely unlikely.

You could try to leave a ping run between your tv and your pc on the lan ip addresses. If the router actually reboots they generally reset the wifi and the ethernet ports so you would lose connectivity. It would show that the router was bad in some way.

I could see buying another router but I still don't understand how you can have 2 already that have the same defect. I mean I suppose the electrical power could drop but you would think you would notice this since it would likely affect the whole house.
 
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Are you actually using both routers in the path at the same time.

If you are swapping them and only running 1 at a time it is very strange. A router could be defective in some way but for 2 routers of different brands to be defective in the same way would be extremely unlikely.

You could try to leave a ping run between your tv and your pc on the lan ip addresses. If the router actually reboots they generally reset the wifi and the ethernet ports so you would lose connectivity. It would show that the router was bad in some way.

I could see buying another router but I still don't understand how you can have 2 already that have the same defect. I mean I suppose the electrical power could drop but you would think you would notice this since it would likely affect the whole house.
I've got 2 routers that I've swapped a couple of times to test them out, I've never used them both. First I was using the Zixel one for a long time, then I've swapped it for the Tenda one for a couple of hours, a similar issue appeared, and then I went back to the Zyxel router. When the connection drops, both of them cannot be reached through the usual 192.168.0.1 IP, and only the first one seemingly restarts itself after 30 seconds (without any info in the logs). The other router can be reached only after cutting down and restoring the power, or after using the windows diagnostics tool that says that the router/modem was restarted afterward (one thing I don't get is how the windows reached the router if I was not able to reach it through the 192.168.0.1).

The part about power outrages came out because I've noticed a couple of sparkles when I plug in something in those sockets. Will try using a different socket, and will try finding the third router to test everything out. Not sure what else can I do from my end.

...
It's been ~5 hours since the moment that I've plugged in the Tenda router the second time, but the internet didn't drop even once, so it is really hard to actually pinpoint the problem. Will update the thread in case the same issue appears (or doesn't). Should I try to find the third router just in case, or is it really that unlikely that the second router out of the box is faulty?
 
The only other thing it might be is something is taking the 192.168.0.1 IP address. That will be a bit hard to find. You might see something if you were to use the ARP command to display the values when it works and when it doesn't. You can also clear the arp and then ping the router IP it should reappear in the table if anything responds. If the router is actually gone the arp entry will not reappear until the router is rebooted. This is play around with the ARP command and see what the mac addresses are and if anything looks strange.
 
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The only other thing it might be is something is taking the 192.168.0.1 IP address. That will be a bit hard to find. You might see something if you were to use the ARP command to display the values when it works and when it doesn't. You can also clear the arp and then ping the router IP it should reappear in the table if anything responds. If the router is actually gone the arp entry will not reappear until the router is rebooted. This is play around with the ARP command and see what the mac addresses are and if anything looks strange.
I've been using the second router, which is Tenda, and I've noticed something quite strange. First of all, it's been whopping 8 hours since I've booted it, and only now the issue appeared. At some point the router simply stopped working, ping cannot reach the address, the internet connection on the PC and other devices (including WiFi-connected ones) disappears, and I cannot connect to the router cabinet through 192.168.0.1 default address. I must note that the actual lights on the router are on and that the WiFi network is available, but there is no internet connection.

Now what is really strange, is that if I run diagnostics after right-clicking on the network icon near the clock, it fixes the problem. The report window says "The default gateway is not available", and that the problem is fixed after restarting the ethernet adapter. Somehow, it fixes the issue with the router, and all of the devices can connect to the internet once again. So the theory of power outrages is off the table, I guess, and it may be possible that something is wrong with the PC or the whole network setup?
 
Yes, our TV tuner is connected via a wired connection too, and as I mentioned, the internet disappears on the TV at the same time as on the PC, so the problem is not with the router->PC connection, more likely with the router/s itself/themselves, or with the modem-ISP part.
Gotcha. Can you connect the tv tuner directly to the modem bypassing all routers? If you can do that and if it's solid, it definitely is a router issue.
 
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Gotcha. Can you connect the tv tuner directly to the modem bypassing all routers? If you can do that and if it's solid, it definitely is a router issue.
Well, I've connected my PC to the modem and everything is completely fine, but when I connect any of those 2 routers - the problems appear, and they are really similar.
 
I've been using the second router, which is Tenda, and I've noticed something quite strange. First of all, it's been whopping 8 hours since I've booted it, and only now the issue appeared. At some point the router simply stopped working, ping cannot reach the address, the internet connection on the PC and other devices (including WiFi-connected ones) disappears, and I cannot connect to the router cabinet through 192.168.0.1 default address. I must note that the actual lights on the router are on and that the WiFi network is available, but there is no internet connection.

Now what is really strange, is that if I run diagnostics after right-clicking on the network icon near the clock, it fixes the problem. The report window says "The default gateway is not available", and that the problem is fixed after restarting the ethernet adapter. Somehow, it fixes the issue with the router, and all of the devices can connect to the internet once again. So the theory of power outrages is off the table, I guess, and it may be possible that something is wrong with the PC or the whole network setup?
Running software on a pc should not fix a actual router issue. I could see it fix the 1 device but it is strange that you could run the command on your pc and it somehow fix the problem for your cell phone at the same time. When you run the diagnostic it will clear some fields and do stuff like renew the DHCP and clear the arp table. You could load wireshark on your PC and capture what the pc is doing. Maybe the pc itself is the problems and it is doing something that is interfering with the router.

This has to be pretty simple though for ping to not work. The method it uses is it checks the ARP table to find the mac address. It then build the ping packet and sends it to the mac address it looked up. The remote end assuming it receives the packet will compare the destination IP in the packet to make sure it him. It will also use the packet to update its arp table if necessary for the return path to your pc. It then builds the response packet and sends it to the mac address.

My guess is one of these arp tables is getting damaged. I will assume you are not running one of the hacker tools that does ARP poison attacks against the router. It is a method that attempt to hijack the default gateway ip address.

It would be very nice if the router let you see detailed stuff but your average home user would not know how to use it so they don't include the feature. Although wireshark can be cumbersom running it when the connection is broken should show very little traffic so it should be easier to understand. Then again if it is not really your PC doing it but another device it maybe not be as obvious.
 

Mr.Spock

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if it's affecting the TV as well it's related to your main router settings vs the ISP. again I would run ipconfig /all to see what the values you're getting for lease times are. and again it may be as simple as rebooting the router via timer overnight.
 
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if it's affecting the TV as well it's related to your main router settings vs the ISP. again I would run ipconfig /all to see what the values you're getting for lease times are. and again it may be as simple as rebooting the router via timer overnight.
The lease time is ~27 hours and it is not related to the happening errors, as I can see. Routers (both) can drop the internet connection a couple of times a day, and I've been restarting them manually, and it didn't fix the problem. I don't think that daily overnight reboots will be useful since the problems still occur after the manual reboots.
 
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Running software on a pc should not fix a actual router issue. I could see it fix the 1 device but it is strange that you could run the command on your pc and it somehow fix the problem for your cell phone at the same time. When you run the diagnostic it will clear some fields and do stuff like renew the DHCP and clear the arp table. You could load wireshark on your PC and capture what the pc is doing. Maybe the pc itself is the problems and it is doing something that is interfering with the router.

This has to be pretty simple though for ping to not work. The method it uses is it checks the ARP table to find the mac address. It then build the ping packet and sends it to the mac address it looked up. The remote end assuming it receives the packet will compare the destination IP in the packet to make sure it him. It will also use the packet to update its arp table if necessary for the return path to your pc. It then builds the response packet and sends it to the mac address.

My guess is one of these arp tables is getting damaged. I will assume you are not running one of the hacker tools that does ARP poison attacks against the router. It is a method that attempt to hijack the default gateway ip address.

It would be very nice if the router let you see detailed stuff but your average home user would not know how to use it so they don't include the feature. Although wireshark can be cumbersom running it when the connection is broken should show very little traffic so it should be easier to understand. Then again if it is not really your PC doing it but another device it maybe not be as obvious.
I've downloaded the Wireshark, but should I run it constantly, or only run it when the internet connection drops and I open the diagnostics fixing thingy? Also, what should I be looking for in the Wireshark data?

When the connection drops the next time - I will check the arp tables, so far there were no problems. I don't run any hacker tools etc, and only 2 devices are connected to the router through LAN - TV and PC, everything else is connected via WiFi (phones).

Is it possible that the new Tenda router is actually faulty and it's just a coincidence that the issue with both routers is really similar?
 
You could be the unlucky guy that happens to have 2 defective routers but before you spend more money you really want to be sure.

Mostly you want to run the wireshark when it is broken and then run the diagnostic thing and see what traffic it is sending to the router that makes the router all the sudden fix itself.

Wireshark is like trying to fill your water bottle with a fire hose. It collects everything and when things are running correctly it is a massive amount of data. There are many option to filter the data but it is a complex tool. Mostly the issue is you will also be learning the fundamentals of network communication at the same time as trying to learn to use the tool. It is a hard thing when you are first starting.

Your goal is to see if anything stands out. It would be interesting to see what the pc is sending and if it receives anything before you "fix" it. Wireshark decodes the packets really well so at least you don't have to do that part, you will know if it sends arps or dhcp requests and what types of response it gets back. You can see all the mac and ip address in every packet being sent.
 
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Well, this is really strange, but I'm currently using my Tenda router, and I've changed the address of the router to 192.168.1.1 instead of 192.168.0.1, and pretty much for the past 30 hours there were absolutely no crashes.

Now I'm really confused with this whole thing lol. Won't close the thread, just in case o_O
 
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Unfortunately, I'm back. A couple of hours after the last post the same problem appeared and I just got mad at the whole problem and returned the Tenda router. I've bought a new tp-link Archer A6 instead of it.

Now, since I'm here, and not enjoying the incessant connection of the internet, it didn't fix the problem. The issue is exactly the same - the connection to the router disappears, and all of the other devices cannot connect to the internet too.

In the arp table the router disappeared at all, there were no other new or duplicate addresses, everything else was the same. Tried to use the Wireshark when I run the windows diagnostics thing, it was showing sending a broadcast through arp protocol " Who has 192.168.0.1? Tell 192.168.0.100", where 100 - my PC, and 1 - the router. After that there is one more packet showing:
"69 2021-01-04 18:36:00,911405 Giga-Byt_f0:6f:3b LLDP_Multicast LLDP 38 MA/b4:2e:99:f0:6f:3b MA/b4:2e:99:f0:6f:3b 0" and I got an error 1617 - "Error while capturing packets: PacketReceivePacket error: This device was deleted.

So I guess that the problem is in my PC or in the network, but how can I pinpoint what is causing this?
 
I suspect that error is the diagnostic reseting the port. If it sends ARP requests like that and gets no response it either means the packet did not really get sent. Ie it failed someplace after wireshark got it. This would be a driver issue. OR the packet was sent but there was no response.

What you might try when it broken rather than use "fix" is to try to ping another device on the network. You can also clear the arp table and see if it gets a response to the ARP. This is different from testing to the router. The router acts as a simple switch when you talk between machines. It is done by hardware in the router so even if the software was having issues traffic should still pass between the machines.

Still this makes little sense. What happens if you just power off your PC or at least unplug the ethernet cable. Do the other devices start working. If this is true then your PC is doing something it shouldn't that is affecting the network. Hard to say since it would have to be something other than standard software.
 
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I suspect that error is the diagnostic reseting the port. If it sends ARP requests like that and gets no response it either means the packet did not really get sent. Ie it failed someplace after wireshark got it. This would be a driver issue. OR the packet was sent but there was no response.

What you might try when it broken rather than use "fix" is to try to ping another device on the network. You can also clear the arp table and see if it gets a response to the ARP. This is different from testing to the router. The router acts as a simple switch when you talk between machines. It is done by hardware in the router so even if the software was having issues traffic should still pass between the machines.

Still this makes little sense. What happens if you just power off your PC or at least unplug the ethernet cable. Do the other devices start working. If this is true then your PC is doing something it shouldn't that is affecting the network. Hard to say since it would have to be something other than standard software.
Not able to ping another device when the connection breaks. So I've cleared the arp table, but the router didn't appear in the arp table after that too. "You can also clear the arp table and see if it gets a response to the ARP". What should get a response to that and how should I check exactly?

Powering off the PC fixed the problem, everything else started working. Also, the system log in this new router didn't have any errors too, everything is usual, the only entries are the devices getting their dhcp ip addresses, etc.
 
That pc has to be doing something really bad to break other devices. If it for example just failed it would not work but would not affect other machines. My only guess would be is the pc is somehow stealing the IP of the router. I guess it could be sending out massive amounts of traffic and crashing the network. Maybe wireshark on the other device would show something interesting.

This thread has gotten long and they all blur together. If it has not been suggested yet maybe boot a linux USB image. That check the hardware. If it fails on a different OS then it is not some window 10 patch messing you up.
 
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An update on the problem.

This problem is persistent for users with B550/X570 mobos that have Realtek 2.5 GbE NICs, and possibly it is a hardware/driver issue.

Theoretical fixes:
  • Installing the last driver through the Realtek website.
  • Disabling Advanced EEE, Energy-Efficient Ethernet, Gigabit Lite, Green Ethernet under the Advanced Tab of the NIC properties (Device Manager, Network Adapters, Realtek Gaming 2.5 GbE Family Controller).
  • Disabling Power-Saving mode in the NIC properties.
Related threads:
reddit.com
forum.gigabyte.us
forum.asrock.com
github.com
github.com

I won't close the thread yet, since haven't tested the fixes myself, and some users said that those fixes didn't help them. Requires a bit more tracking.
 
Not something I would have expected but I have seen other threads talking about different issues with that nic/chip. I guess I never even looked at 2.5g would go to 10g if I really needed more than 1gbit. I guess I have to add this to my never by a mother board list, no killer and now no realtek 2.5g
 

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