I'm using the standard Windows firewall, and turning it off makes no difference. I use AVG antivirus, and tried stop the services running, and it doesn't make any difference either. Neither with Stanza or Calibre content server.
I don't have another computer until in about a week (but I can borrow my neighbour's laptop tonight).
My router is a 3G router; Huawei B970. I found these links:
http://www.huawei.com/mobileweb/en/p...iew.do?id=1880
http://mybroadband.co.za/vb/showthre...70-HSPA-Router
Don't know if it's relevant, but connection worked with my iMac.