Question Strange Issues With Wired Connection After new Modem/Router Install

May 9, 2018
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First off, some basics.

The new Moden/Router is the Netgear Nighthawk C7000.
I have Xfinity gigabit internet (can't remember the exact plan name, but it's up to just shy of a gb/s)
There are currently a total of thirteen devices connected to the router. Six are wired and seven are wireless. Only one device is experiencing issues.

Motherboard: Asus ROG Strix z370f (ethernet is plugged directly into the motherboard)
Power Supply: EVGA Supernova 850P2

The system is running Windows 10 64 bit and is up to date.

The connection is wired, although there are two switches.
Netgear GS308 8-port Gigabit Switch (located by the router)
TP Link TL-SF1005D 5-port switch (A temporary switch and the first thing I would expect to be the problem, except that a second computer is connected to this switch as well and has experienced no connection issues over a good five hours of use.

Alright, on to the actual issue itself. Since installing the new Modem/Router the single system has been experiencing frequent network issues. These can occur anywhere from within five minutes of each other to over an hour apart. The severity ranges as well. I've had several dropouts that resolved themselves after a few moments, but the most common (or at least most noticeable) will prevent me from loading nearly any webpage or online service (more on the "nearly" in a moment). This will last indefinitely but can be immediately resolved by simply removing and re-attaching the cable to the computer. I've also tried and had success with restarting the computer, resetting the switch, and re-plugging the cable on the switch's end. Basically any reset in the chain to the computer seems to resolve the issue immediately.

As for the "nearly," a few website are not affected by the connection issues. The three I've confirmed are Facebook, Google, and Youtube. I've done some research which indicates the issue here may be that I'm specifically having ipv4 issues, while ipv6 remains unaffected.

I checked the Event Viewer for any obvious errors. I noticed a repeating DNS 1014 error, but I was able to solve that with a simple command prompt reset followed by a system restart. Unfortunately I've forgotten the exact command used here, but the DNS error has not returned while the connection issue persists. The other issues in the event log are occasional DistributedCOM and User Profile Service errors. These are annoying but were occurring before the modem upgrade and are likely issues for another time.

A couple of other things I have tried:

Updating the ethernet adapter drivers through the Device Manager. No effect.

An antivirus scan. Came back clean.

So, here I am, thoroughly confused. I'm aware there are some things I have not attempted. The first would be an alternate ethernet cable between the switch and the system, to ensure a faulty cable is not the root cause. Given that only ipv4 seems to be having issues, and the fact that the issues only began occuring after a new Modem/Router install, I doubt the ethernet cable is the root cause. At the moment I don't have a replacement long enough, but I'll be getting one soon just to definitely check this possibility off the list. Second, I have not attempted to connect the system directly to the Modem/Router, with no switches in the way. More or less same as above, I don't have a long enough cable to make the run at the moment. I also doubt this is the issue, since the other system on the same office switch has had absolutely no network issues.

Any help would be greatly appreciated.
 
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Ralston18

Titan
Moderator
Is it possible to swap the two computers without changing anything else?

Just to determine if the problem follows the computer or remains with the network path currently serving the "one device" having problems?

Sketch out a network diagram to establish an overview of how the devices are all connected. Keep an eye on both the assigned DHCP IP addresses and any static IPs that may be assigned. Doublecheck the subnet masks.

Then do indeed start swapping in known working ethernet cables, trying direct connectivity (i.e., bypassing switches). Do so methodically and only change one thing at a time. Use the diagram to note changes and the result of each change.

Hopefully you will be able to narrow down and establish that the problem is either physical or configuration related.
 

doolittle

Distinguished
very odd - what I would do before troubleshooting windows 10 networking issues is to quick confirm windows itself is the issue, get a bootable linux USB like Ubuntu in live mode or Slax which both use DHCP by default so you can have a bootable OS up and running in a jiffy.​
If you can't replicate the problem in linux you probably don't have any hardware probs and can continue to look at resolving the windows problems.​
 
May 9, 2018
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Thank you for the replies. I was able to do some additional testing last night and found that a couple of particular actions could cause the same dropouts. Launching the specific game Black Desert Online would reliably cause my ipv4 connections to drop completely (ipv6 still left unaffected). Some quick research indicates others may have experienced similar issues in the past, and there was a recent report indicating Comcast/Xfinity in particular may be having issues with the game for the past couple of weeks.

More unusually, I found that running a simple diagnostic on the network through the control panel was also frequently causing dropouts (about 3/4 times). This particular issue, however, seems to have disappeared this morning.

I installed Black Desert Online on the other office computer overnight and tested this morning to find that the exact same dropout occurred. The dropouts are not completely reliable. Sometimes I am able to login and play for upwards of an hour, but the same network drop will inevitably occur. I've tested both systems running the game at the same time, and the dropouts are not simultaneous.

Either way, I've ordered a new office switch and some cabling, including a cable long enough to connect either of the systems directly to the modem.

I've also thrown a support ticket to the game's support to see if they have anything to offer. Hopefully this is a switch/cabling issue, but if not I'll probably have to go back and forth between Xfinity and game support.
 
May 9, 2018
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Another small update. Running a network diagnostic appears to immediately fix the ipv4 service loss. This doesn't really fix the issue, but it at least bypasses needing to reset the ethernet cable each time it occurs.
 

Ralston18

Titan
Moderator
Interesting...

On both the original computer and on the other office computer take a look at Reliability History/Manager. And Event Viewer as well.

Good chance that one or both captured some error code or warning related to the service loss.
 
May 9, 2018
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Reliability History has nothing that indicates any network issues. Event Viewer has a bunch of User Profile Service Error 1534 and a couple DistributedCOM error 10016. Both of these have been going on for a while, though, and predate any network issues.
 
May 9, 2018
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Well, another small update. The system is now directly connected to the modem but I'm still experiencing the same disconnects. The cable is brand new as well, so it looks like it's something between Xfinity and the game. Hopefully support from one of those two can provide some answers.
 
This generally is why this is the first test you do. You avoid spending lots of time troubleshooting the equipment in the house when it is not the problem..

There should be a log in the modem that will show if you are getting network outages. The ISP should be able to see these also. You also should have a screen that shows errors on each channel. The key is the number of uncorrectable errors and if you see it increasing a lot. You will always see error numbers but not change very much.....many times you might get a few here and there a hour.

These indicate a issue with the connection.

Run tracert to 8.8.8.8. You then want to ping hop 2. This is the ISP first router. You want to show the ISP that you get no loss ping your router (hop1) but you get loss ping their router.

Note before you have the ISP actually come out check all the connections to the modem. They need to be tight and be sure none have water or dirt in them. You want to remove any splitters and unused cables as you can.
 
May 9, 2018
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Thanks for the reply. I ran the tracert and during the next disconnect pinged hops 1 and 2. As expected, I was able to reach hop 1 fine but hop 2 would time out.

I contacted Xfinity again and finally got through to someone who informed me that the Netgear C7000 is incompatible with Xfinity's gigabit internet, which is interesting for two reasons:

First, I'm fairly certain I originally found the C7000 on their gigabit compatibility list (even though now it's been moved to the 400mbs category).

Second, I was experiencing no issues with the old garbage modem/router combo I was briefly using after upgrading to gigabit but before installing the new hardware.

Either way, they're blaming any issues on this incompatibility and refusing to offer any support until it's resolved, so I guess that's the next step.
 
This is the same reason you can't use for example huawei cable modems on most systems. They likely will work fine but the ISP does not want to support them.

What you will find is most ISP want docsis 3.1 devices on their gigabit connections. I suspect what they are doing say on the 400mbps system is making sure they can deliver 400mbps with multiple people sharing it. They can fit multiple people running at max rate in docsis 3.0.

Now I really doubt that is the problem. Since it generally will not work at all if they are using docsis 3.0 and your modem is 3.1. I guess it depends how they are accomplishing mixing the 2 plans on the same cable.
 
May 9, 2018
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Thanks again for the reply. I wanted to give one final update and the ultimate solution I found, in case anyone else happens to run into this down the road.

I switched my setup over to the Netgear C7800, which was on Xfinity's official list of gigabit approved devices. The exact same issue continued to occur and, if anything, seemed to become more frequent. One of the office systems also began experiencing infrequent ipv4 dropouts that required full modem restarts to resolve.

According to the Comcast technician they finally sent out, he's seen a couple of similar odd issues with Netgear products interacting with their gigabit internet. He hooked up one of their own modems and the issue seems to have gone away entirely. It's ultimately a somewhat frustrating solution, since I'm probably going to want to switch it out down the road for better wireless, but at least it's fixed my immediate problems.
 

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