Check Debian network card

We think we may have a faulty network card on a Debian server. it is a 4 port Gigabit card I350. It works on port 1, but port 2 is not working properly - layer 1 comes up and we can see arp requests going out but that's all, cannot even ping. Need someone who is an expert with Debian / Linux / low level drivers to check this and diagnose the fault. We can give you remote SSH login. We have another, identical server that is working ok you can compare against.