Router disconnects wireless when ethernet port used

mattross · 17 Mar 2008 at 21:26

Here's an odd one. A friend has an SMC Barricade wireless-N router that works fine connected to Virgin Media cable with a laptop. It connects via WPA2 and all is well until plugging in an ethernet cable from a desktop PC into one of the LAN ports on the router. Then the laptop remains connected to the network but nothing appears to work from that point on. Webpage requests that did work then return page not found errors.

Tried three different ethernet cables and all four ports on the router with no effect.

Any idea what's going on?

radderfire · 18 Mar 2008 at 01:09

OK, very much guessing here but thought I'd reply because no-one else has. Clearly, something about plugging in the ethernet is throwing the router into a tizz. Some questions:

- When PC plugged in with ethernet, can it get web pages?

- With the PC plugged in with ethernet, have you then tried plugging in the laptop with ethernet as well, would be interesting to know what happens.

Some thoughts:
- If the PC is Vista but the laptop XP, the Vista of the PC could be affecting TCP/IP protocol on the router, switching it over to IPv6??

- Maybe the PC is affecting the DHCP leasing on the router??

errata · 18 Mar 2008 at 13:02

I'd check the dhcp ranges being issued, possibly the routers only been set up to issue 1 or theres a conflict with the address the router is using and trying to pass on resulting in 1 pc being ok 2 not ok.

Does *** darn thing work with wireless turned off and just using etherent.

mattross · 18 Mar 2008 at 20:48

I'll find out on Friday as I'm getting the whole lot to test myself. I'll try your suggestions and post back.

Thanks.

mattross · 21 Mar 2008 at 11:15

Hmm...it looks like there is no issue with this kit. Got the desktop PC, router and laptop at my house for testing. Everything works as it should. Then I was told at their house they had the cable modem's ethernet AND USB connectors both plugged in. Oops. The cable modem's USB to the desktop PC and its ethernet to the router's uplink port.

Looks like that was the cause for the disconnections. As soon as an ethernet cable was connected between the desktop and the router it would have meant the desktop was connected to the cable modem via two different routes. I'm not a network expert but I'm fairly sure that would be an issue. The modem at best would be confused as to which connection to use and may use USB in preference, thus disconnecting the router's uplink to the internet and breaking the laptop's link as I described in my first post.

Can anyone confirm what happens if both are connected?

Update:

It was the cable modem USB driver causing this problem. Even when not connected via USB it was interfering somehow. Manually uninstalled the drivers by removing the registry keys that detailed the driver and after that no more problems.