Router randomly drops internet connection but still says "connected"

[m33ts4k0z]

Hello,

Since some days ago, my Asus RT-AC88U router randomly loses the internet connection while still saying connected and im able to access it with its local IP address. All the devices connected to the router lose internet doesnt matter if they are wired or wireless. The disconnection lasts about 1 minute and then it is back again.

I'm using the latest ASUS Merlin firmware and while I have the same provider and router for about 1.5 year, its the first problem that this happen.

I have tried to:

Power cycle the router
Reflash the firmware
Restore to factory defaults

I have many devices attached to the router (about 10-15 connected at the same time) but the RAM and the CPU usage of the router stay really low. Any ideas?

Thanks in advance

 

[nitinvaid20]

it can be the internet issue as you are connected to the router and can ping to the local IP too?
have you tried using the internet wired without the router?

 

[androbourne]

Check the cable between the modem and the router (WAN most likely).

Your PCs are not showing disconnected from the internet because it is most likely not dropping LAN connection to the router and the router is most likely the default gateway. So it is connected. It sounds like a WAN drop. Check the modem for issues and try to give that a reboot and also check the WAN cable.

If issues keep happening. Bypass the router and plug a laptop directly to the modem. Do a continous ping check for awhile to an external site like google. If you see a lot of packet loss or pure drops. Call ISP and get a modem replacement.

 

[m33ts4k0z]

Thanks for your answers.

It will really hurt me to connect a single computer to my line in order to check if this is a problem of the router because I run 2 servers and I even use a 16port switch since the built 8ports of the router arent enough for me. That said since the router has 3 years warranty it wont cost me to RMA it but I would leave it as the last resort.

I just bought a new ethernet cable in order to try. The router works when the problem occurs: I can login to the interface and it says connected ( all on my local network say "no internet connection" while the router says "connected". Its WAN LED blinks white which shows internet connection because if there wasnt it would be red instead) and I can ping the local computers and devices.

Since I have restarted, reflashed and restored the router to its factory defaults I will try with the new cable and see. Do you think TTL could also help?

The problem is that this occurs randomly every 2-3 days and it only lasts for max 1 minute but the thing is that there isnt any IP change or anything.

 

[androbourne]

Just because the router is working, doesn't mean there isn't a problem with it. (modem or router).

Normally when either go bad, they still function, you just get really bad bandwidth and traffic flow. Happens all the time.

I don't think TTL would be the issue if you are leaving defaults. It's pretty standardized nowadays.

Did you test the modem like I suggested? (not the router).

 

[m33ts4k0z]

Just because the router is working, doesn't mean there isn't a problem with it. (modem or router).

Normally when either go bad, they still function, you just get really bad bandwidth and traffic flow. Happens all the time.

I don't think TTL would be the issue if you are leaving defaults. It's pretty standardized nowadays.

Did you test the modem like I suggested? (not the router).

I dont have a modem, only a router that connects directly to the wall through a RJ-45 ethernet cable. In order to find out if the router is the problem, I need to connect only 1 computer directly to the wall and since the problem happens once every 2-3 days I need to test it like that for like a week. Something that unfortunately cant afford. I could send the router for RMA and use the router given by my ISP in the mean time. This will keep my servers up and I will also see if the router is really the problem.

 

[androbourne]

The standard is that an ISP would provide an modem\router. If you decide to add your own router, you would normally put the ISP modem in bridge mode and attach your router to the modem.

So something doesn't sound right about your setup unless you are using a business line and have an MLPS...

Have you tried just putting in the ISP router and seeing if that makes a difference?

 

[m33ts4k0z]

The standard is that an ISP would provide an modem\router. If you decide to add your own router, you would normally put the ISP modem in bridge mode and attach your router to the modem.

So something doesn't sound right about your setup unless you are using a business line and have an MLPS...

Have you tried just putting in the ISP router and seeing if that makes a difference?

In Sweden you are not forced to buy a router when picking an ISP. The only reason I got one from them is because I also use VoIP from them and the RT-AC88U doesn't have RJ-11 telephony ports. Otherwise you are not obligated to use their equipment since most of the houses/apartments have fiber connections as I have 1/1Gbps.

There is nothing strange with my setup since it has been working like this for almost 2 years. Right now I have my router as the first router and my ISPs router is connected to it in order for me only to get calls and nothing more. It would certainly work as you suggest by bridging it but I dont see why I would try that now while everything was working fine for so long.

I think that I will give it a shot with the new cable and if this occurs again, I will, in the end, use my ISPs router and wait for some days to see if this solves the problem before I send my RT-AC88U for replacement.

 

[androbourne]

In the USA most IPS don't charge us for a modem either. It is provided during installation.

I think the difference here is we have access to our modems and you do not. Every end point has to have a modem of some type to properly route the traffic to you, it is how a WAN address is delivered to you directly.. I'm just guessing your modem is an MPLS coming from the hub or street corner and not an actual modem you have access too.

In this case. A direct connection to the inbound cable from the ISP to your house will tell you if issue is with ISP or not . As you are bypassing the router and plugging straight into the ISP modem.

 

[m33ts4k0z]

In the USA most IPS don't charge us for a modem either. It is provided during installation.

I think the difference here is we have access to our modems and you do not. Every end point has to have a modem of some type to properly route the traffic to you, it is how a WAN address is delivered to you directly.. I'm just guessing your modem is an MPLS coming from the hub or street corner and not an actual modem you have access too.

In this case. A direct connection to the inbound cable from the ISP to your house will tell you if issue is with ISP or not . If issue your own router. As you are bypassing the router and plugging straight into the ISP modem.

If the topology is the issue why did it come up the last month and not the past 20? The only thing changed is some firmware updates on my router but there is none else complaining over at ASUSmerlin's forum.

 

[androbourne]

The topology isnt the issue... I'm simply saying just bypass your router and plug straight into the incoming WAN. This is how you test for ISP related issues with a direct connection. If your router is dying it may still function but limit bandwidth and cause these exact issues... this is how you determine if its the router or ISP.

The topology is the same. You simply don't have direct access to the modem as the ISP is handling that on the back end. In the US, we get direct access to the modems.

 

[m33ts4k0z]

The issue was some electricity... Strange but the router was behaving very akward at the point that some of the ports werent working correctly or not at all. That router has 2 integrated switches (1 from Asus and 1 from Realtek) and the latter was causing issues. The solution was to power cycle the router(removed the power cable and turned it on, turned it off, put back the power cable and turned it on as normal) and everything was working correctly afterwards.

 

[androbourne]

Glad you got it figured out.

As part of troubleshooting. If you were to do as I recommended it would have ruled out a modem issue and allowed for us to work directly with router as we would have verified that to be the issue.

I'd recommend you keep an eye on it and if it happens again to get it replaced before it dies.

 

[m33ts4k0z]

Glad you got it figured out.

As part of troubleshooting. If you were to do as I recommended it would have ruled out a modem issue and allowed for us to work directly with router as we would have verified that to be the issue.

I'd recommend you keep an eye on it and if it happens again to get it replaced before it dies.

Well, this situation wasn't at all resolved by powercycling the router/switch...

since my last post I performed many tests to figure this out. I did get a brand new router after contacting Asus Sweden but this didn't solve it. I also changed all the cables on my home network without any results. As a move of despair I even changed my switch with a new one. At some point I even had doubts that my servers motherboard was at fault so I found an excuse to perform a little upgrade and got a new mobo/CPU. That was the point where a man goes insane as nothing worked.

Then I thought that I will start "simplifying" my network in order to isolate the issue.

The first thing I tried was to remove my ISP's router that as I said I solely have for telephony. And... It Worked!

So after removing my ISPs router completely from my main Asus router and being able to access the Internet without any issue for more than 5 days, I performed a reset on my ISPs router and tried plugging from my Asus LAN port to my Tilgin's WAN port exactly as before but this time I put the "WAN" settings manually, setting the IP to static, telling the Asus's one to perform a static DHCP on that one and after about 2 weeks, my network is performing perfectly fine without drops.

So bottom line, one of the following things happened:

1) There was a DNS conflict on my ISPs router (Tilgin) on my network since it was maybe using the ISPs DHCP while my Asus router was using Google's. This is unlikely not only because the Tilgin router was getting the DHCP from my Asus router and my ISP doesn't bake their DHCP in the firmware, but also because such an issue wouldnt create this behaviour.

2) The issue was caused because I was stupid enough to use the same IP range (192.168.1.0) on both routers so they were both trying to give an IP that was already in use. While this makes much more sense, I don't recall changing the settings of my Tilgin router(ISP's) since this issue started happening back in November. That certainly doesn't mean that I didn't. Anyway, changing the range to 192.168.2.0 on my Tilgin and everything works fine for many days now.

I just leave this comment in case someone come across a similar situation and are at a loss.

 

[technerd]

Well, this situation wasn't at all resolved by powercycling the router/switch...

since my last post I performed many tests to figure this out. I did get a brand new router after contacting Asus Sweden but this didn't solve it. I also changed all the cables on my home network without any results. As a move of despair I even changed my switch with a new one. At some point I even had doubts that my servers motherboard was at fault so I found an excuse to perform a little upgrade and got a new mobo/CPU. That was the point where a man goes insane as nothing worked.

Then I thought that I will start "simplifying" my network in order to isolate the issue.

The first thing I tried was to remove my ISP's router that as I said I solely have for telephony. And... It Worked!

So after removing my ISPs router completely from my main Asus router and being able to access the Internet without any issue for more than 5 days, I performed a reset on my ISPs router and tried plugging from my Asus LAN port to my Tilgin's WAN port exactly as before but this time I put the "WAN" settings manually, setting the IP to static, telling the Asus's one to perform a static DHCP on that one and after about 2 weeks, my network is performing perfectly fine without drops.

So bottom line, one of the following things happened:

1) There was a DNS conflict on my ISPs router (Tilgin) on my network since it was maybe using the ISPs DHCP while my Asus router was using Google's. This is unlikely not only because the Tilgin router was getting the DHCP from my Asus router and my ISP doesn't bake their DHCP in the firmware, but also because such an issue wouldnt create this behaviour.

2) The issue was caused because I was stupid enough to use the same IP range (192.168.1.0) on both routers so they were both trying to give an IP that was already in use. While this makes much more sense, I don't recall changing the settings of my Tilgin router(ISP's) since this issue started happening back in November. That certainly doesn't mean that I didn't. Anyway, changing the range to 192.168.2.0 on my Tilgin and everything works fine for many days now.

I just leave this comment in case someone come across a similar situation and are at a loss.

I am having exactly the same issue as yourself with the exact same setup, except I have a VDSL line instead of fibre.

My network goes VDSL ->modem ->RT88U ->ISP router for VoIP.

My Asus drops the connection daily and a restart fixes it. I have also tried another Asus (rt87u) with the same result.

I am going to try removing my ISP modem for VoIP, but it is already on a completely different subnet and has a static IP so I don't know what to expect.