I've switched things around a bit and tried the powerline adapters in dedicated sockets. I'm still only getting around 60mbps, but I presume it's because the sockets are basically at opposite corners of the house. At least with this set up, my PC can connect to the now-access point router via wifi (as well as the headset) and it doesn't seem to get knocked off anymore. I cancelled the PCIe card and ordered a wifi repeater, so tomorrow I can try that, repeating the wifi from downstairs and connecting it to the WAN port of my router via ethernet, and then having my PC plugged into the same router via ethernet. That should work, right?
Thanks
Thanks