Router problem seems to be sorted now.
I have connected it via port 1 with a crossover adapter on the cable.
That seems to work for the PC.
I will have to wait till I can get a crossover cable to replace it with then I can have the adapter back for the xbox cable (already xover & runs throughout the house) to make it a straight through one again.
Cuts the number of available ports to 3 now though.