WAN Specific Quirks
Its the dreaded Nvidia 100/10 Mbps PCI Ethernet Card. I can't give you a model number, because it is allready jamned into a tiny laptop motherboard.
This card refuses to connect to the WAN, but works perfectly well on the LAN.
I have tried every single setting combonation possible, but it refuses to maintain or setup a link.
I have called my ISP, and they said it was the cards problem itself, I tried switching cables, and rebooting everything.
So it failed to even establish a link with the wan, on the most basic setup of DHCP.
I tried swapping my WAN interface for my LAN interface, and whamo, it works.
My LAN interface is not the same NIC, it is a seprate usb attached 100/10 Mbps ethernet NIC, that is some generic brand.
But for some reason, the new generic WAN NIC only works when I set the setting to forced 100baseTX full-duplex.
My modem is 1000/100/10 baseTX full-duplex autoselect, so I do not know why it would not work normally.
There is nothing wrong with the modem itself, I had it replaced with the newest model, and inspected/tested after it had arrived at its final resting place.
The Nvidia LAN NIC works absolutly fine in auto-select (default), on a 1000/100/10 baseTX full-duplex autoselect network.
So if somebody could explain to my why this weird behaviour might be happening, that would be greatly appreciated.
Hmm, seems like your modem might not be doing auto-select quite as well as it reports.
As a test I would try putting a passive switch in between the Nvidia NIC and the modem.
I would recommend using a managed switch and VLANs over a USB NIC everytime anyway so that could be a solution.