We still don’t know why the on-board nics don’t auto-negotiate correctly if the switch stack is rebooted. We have at least 20 servers with the same hard ware spec/configuration and all the add-on nic cards exhibit the same behaviour.

Thankfully, once we sorted out the stack issue, we have never had to reboot it again since!

Thanks for taking the time to reply. The issue actually was cause by a faulty backplane cable that was used to connect the switches into a stack. The traces and logs never showed an error. But replacing it, did.

If you are using nortel 5510/5520 baystack switches, they autonegotiate perfectly with all new equipment.

Your problem will occur if: cables are damaged/not punched-in correctly or are not connected properly in any way. Or if the signal is too weak due to attenuation caused by the distance of the cable.

You must make sure that you are using fully straight-thru cable configuration between the switch and the server. You must also make sure you are using CAT6 cables.

Alternatively, you may use fiber, which is more expensive but does not have the same L1 issues as copper cables.