Bizarre modem problem

[Chaosphere]

I'm using a Zyxel Prestige 660RU-T1 modem, supplied by the service provider, and I am having a frustrating problem for the last couple of months without any real reason why.

I have the modem beside the phone socket, and a 7m ethernet cable running to the PC. Through this, there is no connection. Packets are sent, but none received. However, the moment I plug a laptop into the USB socket on the modem (while the ethernet is still connected), both the PC and laptop have perfect connection.

This leads me to conclude that my ethernet cable and network card are in working order. Also, I have replaced the modem with an identical model and this has worked in the exact same way. We had this problem with another modem, a few months ago, and the SP replaced the modem. So we're talking about 3 Zyxel modems having the exact same issue.

Is there any logical reason why this is happening? Even any theories?

Thanks a lot,
Fionn

[F1]

Have you tried ipconfig? It's possible your Network card is retaining an out-of-date IP address

[scraphog]

heres a theory, and its just that.

picture inside the zyxel, two paths to the firmware, one from usb and one from ethernet, yet at the ports themselves they are connected to a wiring harness (a bridge )...teh path inside the router from the bridge to the firmware on the ethernet side has an issue, the path on the usb side is fine, when the power lead from the usb side is plugged in, teh bridge is using the usb to firmware path and making the connection for both ports...it is a grounding out issue in the Zyxel, try upgrading the firmware, if no resolve, then change the device.

does the laptop have an ethernet port, if so, unplug the wire from the pc and plug in the laptop...results? It shouldn't work if i am correct.

[Chaosphere]

Your theory is logical and makes complete sense. I upgraded the firmware (although it's from last November), but still nothing.

Could this be a problem with Zyxel modems in general, since I've had this issue with three of their modems?

[Mathster]

are you getting your link light when the LAN cable is plugged in?
here is a link to the manual. IE didn't like to download it, but I finally got it. the file is too large to attach.

[Chaosphere]

Thanks for your efforts to get the manual, but unfortunately it's the exact same one that came with the modem, and doesn't give me any enlightenment.

All of my connections have been made according to the pictures in the manual. The network card in my PC is about 4 months old, and the ethernet cable is new too.

There seems to be no logical answer to this problem, especially since three modems have the exact same issue.

[TurcoLoco]

I agree with Scraphog, the problem sounded like a 'shorting out' type of a problem. It doesn't make any sense for both connections to come alive when USB is connected as well.

Along with what Scraphog suggested, what happens when you plug the RJ-45 coming from the modem to the laptop that normally connects with the USB cable, any connection then?

Also what happens when you connect either the desktop or the laptop alone using the USB cable, any connection then?

Another thing, the problem could be related to the info you briefly mentioned here:

I have the modem beside the phone socket, and a 7m ethernet cable running to the PC.

This modem is a DSL modem, I take it? If so, is it connected directly to the phone outlet on the wall or are you using a splitter of any kind? Can you connect to modem to another outlet to see what happens?

~TL