[blueturtl]

I have an ADSL modem+router combo device:
ZyXel Prestige 660HW-61

Recently I found that the LAN ports are no longer functioning properly.
It took a long time to arrive at this diagnosis, because my second rig -- an ancient AMD K6-III was/is connecting just fine. Later it turned out, it is in fact the only computer that CAN connect.

It is a hardware level problem I suspect, because the port indicator leds will not light up when a cable is plugged in. The client computer will behave as if the cable is unplugged.

First I thought one particular port was broken, but I've connected the AMD rig to all ports for testing, and sure enough it works on all of them.
Any other rig that I connect will stay on a perpetual cycle of trying to obtain an IP address and never getting it. Yes, I have tried switching cables, rebooting clients AND the router..., etc.

The wireless is working just as well as it ever did.

[TerryNet]

Sometimes a NIC will not auto negotiate a bandwidth with a particular router (or modem or switch). In Device Manager right click on the ethernet adapter - Properties - Advanced tab. If there is a "speed & duplex" property try different values, starting with 100 Mbps full duplex and 10 Mbps full duplex.

[blueturtl]

But why would I now have to go to all that trouble, when it worked automatically before?

I guess I'm kind of answering my own question. If nothing has changed, the router must have taken damage from something...

[TerryNet]

But why would I now have to go to all that trouble, when it worked automatically before?

I have no clue. Just reporting virtual* observations. Seems to be rare, but sometimes auto negotiation doesn't work from day one and sometimes it fails later. Maybe because of aging, maybe from damage, ...

* "Virtual" because I've "seen" it happen on threads here, not in person.

[JohnWill]

I've seen this in person, and in one case it did happen after the equipment was installed for at least a year. Never did find out why, but I stuck a $10 Ethernet switch between them and it was all fixed.

[blueturtl]

JohnWill, thank you for making me feel less crazy.

I'm circumventing the problem by using another wireless router in client mode to connect to the modem (since the wireless on the modem still works). This allows me to attach the wired client computers to our LAN without having to mess with wireless drivers or configuration on each client.

<ADSL modem> <--wlan connection--> <WLAN router> <--wired connection --> <client PC(s)>

[JohnWill]

Computers are strange things.