Wired Network Configuration

[byalexandr]

Hey all,

 

I recently moved to a new house and it has CAT5e ports throughout the house routing to a patch panel in one of the closets. The house has a 1 gigabit fiber connection and we are using AT&T Fiber with their provided modem router. I had the technician set up the router in the living room, where I have one of the Ethernet ports on the router going back into the wall where it then connects at the patch panel. At the patch panel, I have an 8-port unmanaged switch connecting the wired devices around the house. In the router, I had set my DHCP range to 192.168.100.xxx instead of 192.168.1.xxx since I had issues connecting to my work server VPN (I work remotely) as the router and work servers were using the same IP. Up until now it's been working fine, but I figured I would mention that since I'm not sure if that's what's causing the issue. The DHCP server range is set to 100.64 to 100.253, with the host device (router) address being 100.254. Everything worked great for a few days, and the fiber connection is obviously very fast.

 

Anyways, today I noticed issues with the connection randomly dropping. I am using a Dell XPS 15 with a USB-C to Ethernet adapter, and I would go about 10 minutes before the Ethernet would disconnect and the laptop switches back to WiFi (which is atrocious compared to a wired connection due to how far the laptop is from the router). I would check other devices also on the wired network, and they too would be disconnected, so that ruled out any issue with the Ethernet adapter or my device. Being that the WiFi still worked fine, I turned the switch at the patch panel off and on again, which would work and restore the wired connection, and then 10 minutes later the connection drops again.

 

The next step I took is I figured the switch may be faulty, so I put in an extra 5-port switch I had laying around just to see if that was the issue. Even with the different switch, it is still doing the same thing. Whenever I check the router settings, I can see my wired devices and their assigned IPs, but the connection status is set to off (when the issue occurs). Again, unplugging the switch and plugging it back in at the patch panel will work temporarily, then shortly after all of the wired devices disconnect.

 

I am not a pro when it comes to networking, and based on my testing this seems to be more of a software config issue than anything with the hardware. I am assuming when I disconnect the switch and reconnect the router is assigning new IPs, but then something happens and the connection is dropped.

 

Would it be worth trying static IP assignment instead of a DHCP server? Would this mean I would have to assign an IP to every device, including the ones using WiFi? And is this done solely through the router settings or would I have to configure each of the devices with the assigned IP? 

[Allan B]

Your assumption this is a software issue not correct.  If the wired connections on all your wired devices are going offline at the same time this is a hardware\wiring issue.

If power cycling the switch (both of them) fixes the issue there are a couple possible causes, which involves the same steps.

 

Step 1 - Disconnect everything from the switch except for the router and the laptop where this can occur every 10 minutes.   You must physically unplug ALL all other cables, even if nothing is on the other end of that cable (that is important).   Does this fix it?  Does the issue return?

   If the issue still occurs, move the laptop to another wired location in the house and test only that cable connect to the switch (and the router) does the issue return?

   If the issue does note return, slowly one by one connect your other wired devices to the network until the problem comes back.   Then you will know which device\network cable is causing the problem.  you can then try using your 2nd switch at the other end of that "problem connection" to see if that helps.

 

There is also the possibility if your cable runs are very long that either switches do not have enough power to run everything, one other thing to try is to use both switches at the same time, connect 2-3 patch panel cables to each switch and then connect them together.  Try to spread out the longest cable runs across both switches.  See if that helps.

 

 

 

[byalexandr]

6 hours ago, Allan B said:

Your assumption this is a software issue not correct.  If the wired connections on all your wired devices are going offline at the same time this is a hardware\wiring issue.

If power cycling the switch (both of them) fixes the issue there are a couple possible causes, which involves the same steps.

 

Step 1 - Disconnect everything from the switch except for the router and the laptop where this can occur every 10 minutes.   You must physically unplug ALL all other cables, even if nothing is on the other end of that cable (that is important).   Does this fix it?  Does the issue return?

   If the issue still occurs, move the laptop to another wired location in the house and test only that cable connect to the switch (and the router) does the issue return?

   If the issue does note return, slowly one by one connect your other wired devices to the network until the problem comes back.   Then you will know which device\network cable is causing the problem.  you can then try using your 2nd switch at the other end of that "problem connection" to see if that helps.

 

There is also the possibility if your cable runs are very long that either switches do not have enough power to run everything, one other thing to try is to use both switches at the same time, connect 2-3 patch panel cables to each switch and then connect them together.  Try to spread out the longest cable runs across both switches.  See if that helps.

 

 

 

Oddly enough, when only my laptop is connected to the switch (and the router of course), there is no issue with dropping connection. Same with other laptops using the switch, when only one device is connected the connection works fine. As soon as I plug in two devices, the connection will drop in and out on both machines randomly (on the other switch, the time between connection drops will vary, but still present the same issue).

 

So based on this it is something to do with the switch, leading me to believe the switch is not doing its job correctly and something is getting hung up causing the connection drop. Using other ports or shorter patch cables with the laptop near the switch did not make any difference, as long as there were two or more devices connected to the switch (and either switch and with short patch cables, for that matter), the issue started appearing.

 

Both of the switches I am using are unmanaged, if that makes any difference. The smaller 5-port switch is a consumer grade Netgear, the larger 8-port switch is a "business" grade Netgear. I can see the activity lights on the ports/cables appear idle, meaning there is a connection, but no data transfer occurring. When the connection drops, the device IPs in the router appear offline.

[Allan B]

If you have multiple switches, multiple cables and multiple computers, then the only common thing left is your router.  It sounds like an arp cache problem or something weird, possibly defecting hardware in the router, memory or processor. 

 

Unplugging the switch effectively downs the routers LAN port which may fix it.  Next time it happens try unplugging the cable between the router and the switch and reconnect it.  Does that resolve it without a power cycle?   Does your router have multiple ports?  try using another one.    Otherwise i would suggest at this point a new router,

If you are using your ISP provided modem\router, maybe call them and see if you can get a replacement. 

If you are using your own router, does the ISP Modem support being a router?  If yes, i would suggest trying that.

[byalexandr]

After some more testing, I found it was the router/modem at fault. After eliminating the switch entirely and plugging directly into the router, it would still drop connection after a couple minutes. AT&T said everything was fine (of course they would) but sent out a technician anyways and he replaced the router. It's been working great since then.

 

As a side note, I wish AT&T would stop giving consumers ancient routers, I mean the router control panel is the same exact software as the DSL router I had 10 years ago. Anyways, fiber Internet is great.

[byalexandr]

Hate to open this thread again unfortunately, but after a few days, the NEW router that the tech switched out is doing the same thing. I have a funny feeling this will turn into a cycle of the tech coming out every 3 days to replace the router since AT&T will never upgrade their hardware, so I probably need to figure out a different solution.

 

I did some reading, and the gateway/router that AT&T provides handles the ONT and modem/router in one unit. I'm not exactly sure how it works, since the fiber interface is actually outside the house and all that is going into the router is a standard CAT5e cable, but the input does say ONT on the gateway. Supposedly, you cannot run your own modem and router because the gateway they provide authenticates with the ISP, and even running your own router with their device in passthrough mode requires their device to still be present in the network.

 

However, given that this is an issue with the router, and potentially not the gateway itself (as it never drops broadband connection to AT&T, even though it drops connection to my wired devices), would running a much better router with the gateway in IP passthrough mode potentially solve the issue? If it's a possibility, I could go and buy a new router (and also boost my WiFi range with something more modern i.e. high gain antennae), but if not, I won't go out and waste a couple hundred bucks on something that won't solve the issue.

 

Starting to get really frustrated because as big as (as massive, rather) a company as AT&T is they have the cheapest, most rudimentary hardware and customer support I've ever seen. Unfortunately there's not many other options as AT&T has their fiber in the entire neighborhood... Working from home though it's an absolute must that I have stable and reliable Internet connection.

[Alex Atkin UK]

23 minutes ago, byalexandr said:

However, given that this is an issue with the router, and potentially not the gateway itself (as it never drops broadband connection to AT&T, even though it drops connection to my wired devices), would running a much better router with the gateway in IP passthrough mode potentially solve the issue? If it's a possibility, I could go and buy a new router (and also boost my WiFi range with something more modern i.e. high gain antennae), but if not, I won't go out and waste a couple hundred bucks on something that won't solve the issue.

Hard to say, given its not clear where the issue is coming from.  It might, if its a software issue, but probably wont if the switch in the gateway is causing the problem.

 

I'd still be tempted to blame bad cabling or terminations in the patch panel over the gateway or switches, the gateway shouldn't be able to cause the physical ports on the switch to bounce (other than the one its plugged into), that's down to the switch and the network interfaces.  As long as the port going from the gateway to the switch stays up, I'd pretty much say the gateway is probably doing its job.

[Donut417]

22 hours ago, byalexandr said:

Supposedly, you cannot run your own modem and router because the gateway they provide authenticates with the ISP, and even running your own router with their device in passthrough mode requires their device to still be present in the network.

That is correct. The AT&T gateway is the ONT and its what will authorize you on the network. IP passthru mode is generally the best option if you want to use your own router. 

[byalexandr]

23 hours ago, Alex Atkin UK said:

Hard to say, given its not clear where the issue is coming from.  It might, if its a software issue, but probably wont if the switch in the gateway is causing the problem.

 

I'd still be tempted to blame bad cabling or terminations in the patch panel over the gateway or switches, the gateway shouldn't be able to cause the physical ports on the switch to bounce (other than the one its plugged into), that's down to the switch and the network interfaces.  As long as the port going from the gateway to the switch stays up, I'd pretty much say the gateway is probably doing its job.

While I would honestly rather it be a wiring, switch, or patch panel issue, the problem persists when a device is connected directly to the gateway with a short patch cable, and on any device that has a wired connection. The technician that replaced the router said it is a common problem with these older units that AT&T uses.

[byalexandr]

1 hour ago, Donut417 said:

That is correct. The AT&T gateway is the ONT and its what will authorize you on the network. IP passthru mode is generally the best option if you want to use your own router. 

If it’s the built in switch on the router/modem/gateway that is causing the issues though, would the problem just move downstream to the new router?

[Donut417]

12 minutes ago, byalexandr said:

If it’s the built in switch on the router/modem/gateway that is causing the issues though, would the problem just move downstream to the new router?

Cant say. I dont have experience with their gateway. I have heard that at least their older gateways were found to be "limited". 

[Alex Atkin UK]

33 minutes ago, byalexandr said:

While I would honestly rather it be a wiring, switch, or patch panel issue, the problem persists when a device is connected directly to the gateway with a short patch cable, and on any device that has a wired connection. The technician that replaced the router said it is a common problem with these older units that AT&T uses.

That's certainly concerning, as when routers/gateways have this problem its usually specific NICs and putting a switch in the middle is the solution.  If it wont even keep the connection to a switch, its fatally flawed and I can't see any way to fix it other than moaning at them until they find a unit that actually works.

[byalexandr]

Further updates, I had my dev team/IT at work remote in and poke around. We played with a lot of settings and tried several different things to resolve it, to no avail. It would still randomly disconnect the Ethernet.

 

I called AT&T again, and this time instead of sending another tech to replace the router again, the service rep just reset the router to factory settings remotely, stating it was unlikely that two routers in a row would have the exact same issue. This included removing the DHCP server configuration we had put in place.

 

Suddenly, all is well again. I tested for several hours and not once did any device lose connection. My VPN seems to work fine, though my dev team tells me I may have problems in the future if the DHCP decides to assign an IP that is the same as the VPN server.

 

I was wondering how changing the DHCP server IP range and router address caused this issue. But, since it’s working, I won’t bother changing any settings. Very strange though that that was the solution.