Ethernet stops working when Virgin router is plugged in

[akistzortzis]

I have a relatively simple ethernet at home. Almost every room has an ethernet cable. In the middle of the house there is a Wireless Access Point. There are two wired network printers. All those ethernet wires (Cat5 or Cat6) and devices meet at a Netgear 8 port 1Gb router. I have two broadband routers, one is TalkTalk and the other is Virgin Media. Both are also connecting to this central Netgear router.

You can connect to the network either wired or wirelessly. Once connected you can "see" and ping all devices on the network, the wireless routers, printers, other laptops and PCs, the two broadband routers, in short everything can see everything.

Occasionally however, the whole wired network goes down, meaning nothing can ping anything else.

I have traced the issue to the Virgin broadband router. If I switch it off, or if I unplug its ethernet lead then the network comes back to life instantly. If I put it back on within seconds the wired network goes down.

This happens with a variety of central routers, I also have an 8 port 1Gb Edimax and another make I now forget.

It would seem that the Virgin Media router, sometimes, does something that manages to take down the whole wired network, even though it is only a node on the network, it is not needed or used to bridge anything. I have of course replaced the ethernet leads and this is not the issue.

Also, this problem does not happen all the time, but occasionally. And before I traced it to the Virgin Media router, it was many hours scratching my head trying to determine how it was possible to lose wired ethernet connectivity between the devices hard-connected in the house.

Any ideas?

 

[Alabalcho]

Are you saying you are feeding two ISPs (with two router) into the same network?

 

[akistzortzis]

Are you saying you are feeding two ISPs (with two router) into the same network?

The ISP modem/routers connect to the broadbands on one side. On the other side they both connect to a central switch. Their LAN addresses belong to the same subnet. They are just two separate gateways on the same LAN.

But that is irrelevant for my problem. The problem is that the switch "freezes" when I plug something into it. The switch has 8 ports, allowing all its ports to talk to each other. But when I insert something into one port, all the ports stop working. This "something" happens to be the Virgin modem/router. I have checked the cable and it is not that.

It does not happen all the time, but only extremely occasionally. The morning that it happpened:

I switched the switch off and on 2-3 times. No fix.
I unplugged the Virgin router's lead from the switch leaving all other cables in place. Fixed.
I re-inserted the Virgin router's lead into the switch. Problem reappeared after 2 seconds.
I switched off the Virgin router. Problem fixed. But after a while (a minute?) the problem reappeared.
Eventually it took 3 or more reboots of the Virgin router to fix the issue.

I was told on another forum that there are EEE and power saving specs that switch off ethernet ports to conserve energy and if there are bugs in the software, on either side of the cable connection, then these things happen.

 

[Joe Porter]

Have you turned DHCP off on the Virgin router?

 

[Alabalcho]

When you plug ordinary PC into one of the eight ports on your ISP router, does it still works? Do you get Internet access on that PC?
What you need your Virgin router for, if you already have Internet service?
Do you want to use it as WiFi extender? Do you want to create isolated network?

 

[akistzortzis]

When you plug ordinary PC into one of the eight ports on your ISP router, does it still works? Do you get Internet access on that PC?
What you need your Virgin router for, if you already have Internet service?
Do you want to use it as WiFi extender? Do you want to create isolated network?

When the problem happens it is almost as if I have disconnected all 8 ports from the switch. I say "almost" because the lights are on and the devices think their ethernet cables are connected. Basically the switch stops passing packets from and to all the ports.

 

[Alabalcho]

You still did not answer my question:
- what do you use that Virgin router for - another ISP, of WiFi extender?
Also - when you plug that router in, do you see change in IP configuration of PCs already connected to the primary router?

 

[akistzortzis]

Nothing connects directly to the two ISP modem/routers. For anything to talk to anything else, eg printers, laptops, phones, and modems, it has to go through the central switch. If we power down this central switch nothing will be able to see or talk to anything else. The two ISP modem/routers are just two gateways and their WiFi is switched off.

The problem is similar to disconnecting the switch even though it is on and the lights are on. The LAN is a Star configuration with this switch in the centre.

If we power off the switch then nothing will work - you asked about DHCP and so on, when the switch is offline there is no physical connection between anything in the house.

The switch's purpose is to isolate the ports, so even if one port has a dodgy cable or other electrical fault, the switch will ignore it and it will not affect its other ports. In theory. That is why there are switches that cost £10 and others that cost £1000.

I suspect a denial of service problem, maybe the Virgin router went mad for a while and flooded the port on the switch effectively rendering the switch offline, but that's a theory. Or it may be something like a weird ground loop / leak problem originating at the Virgin modem/router which affected electrically the port on the switch.

 

[notneps]

The LAN is a Star configuration with this switch in the centre.

Are you saying you have the main router and the two broadband router/modem combos (each with its own internet connection) all plugged into the switch via their LAN ports?

 

[akistzortzis]

Yes, almost. the "main router" is the "central switch", not a router, but a switch. There are other switches at other parts of the house to act as hubs and connect multiple devices to the LAN. However there is a central switch which has everything almost connected to it. The two ISP modems are connected to this switch through their LAN ports. I have two ISPs for redundancy. Typically I switch only one DHCP server on one of the ISP modems, and that modem becomes the gateway for most devices around the house. But you can always override this on your laptop/android and choose the other ISP as a gateway. They are both on all the time. This system has been working like this for many years. The two ISP modems/routers and everything else share the same subnet. So 192.168.0.1 is the Virgin gateway, 192.168.0.2 is the Talktalk gateway, 192.168.0.3 is the WAP in the loft, 192.168.0.4 is the WAP on the piano, and so on. Most people connect to the WAP in the loft 192.168.0.3. One of the two ISP modem/routers will serve the DHCP addresses. Other devices are hardcoded to choose one ISP or the other depending. Windows PCs/Laptops can switch by the click of a button, on the Androids and iPhones is a little harder. Typically I use the slower Talktalk for the main TV/Amazon Fire TV/Netflix, and Virgin for everything else. But recently Virgin has been playing up (the ISP not the router) and so all my traffic is now through Talktalk.

However in that early morning, the Virgin router/modem decided to be funny and somehow bring down the central switch, without which nothing can talk to anything else. I figured this by trial and error unplugging one cable at a time from the back of the switch until I found the culprit. With the Virgin lead removed from the back of the switch the switch instantly came back to life. Re-inserting the offending cable at the back of the switch and within 2 seconds the switch stopped. Swithcing off the Virgin router and all is fine. Switch the Virgin router back on and after a while switch goes down again. In the end it took me 3-4 power cycles of the Virgin router before it became stable. And since the Virgin router has the ability to stop the switch, it could be doing it again, in small doses, and I probably would not know it.