We already talked about that ... like ... eight months ago? :confused:
Japo has a point here:
Your router releases the IPs by DHCP, right? You tried to switch the ports and give manual IP adresses to check the connection.
If the problem stays with the laptop the prob has to be on the laptop.
Here's something:
There was this workstation in the domain at work and it would always refuse to keep up the Citrix-connection (ica-protocol).
Solution was replacing the facy ass onboard network card (with an integrated FW and loads of shitty stuff) with a usual network card.
Now, replacing the NW-card on a laptop is difficult... PCMCIA could be a solution...?
Hope this helps.