For anyone that is still struggling to connect to an opponent, i have found a fix that has worked for me.
I connect wirelessly and within 'Network Connections' under 'LAN or High-Speed Internet', i right clicked on 'Local Area Connection' and selected 'disable'. I'm using XP, i think you just have to disable anything that is not in use under 'LAN or High-Speed Internet'. Has deffo worked for me, hope it helps anyone who is having the same problem.