[jem]

Now I'm not actually sure that it's possible to find what access port you are connected to via any TCP method. APs are layer-2 devices not layer-3 (unless they are doing something odd) so for example they won't show up in a tracert.

I was once in a similar position with a company which had 22 Netgear APs dotted throughout the office and what I ended up doing was to look at the configuration pages for each AP and see which machines (listed by MAC address) were associated with each one. It's not as arduous as it sounds since you can start with the one physically nearest the problematic computer and work outwards from there until you find the MAC address of the PC listed.