Connection Issues with new wireless adapter

Greetings,

My old router and adapter were not getting me the bandwidth I should have been getting (20mbps instead of ~50mbps). So I recently purchased a new router (a linksys EA4500) and it's companion adapter (model AE3000).

First it was giving me tons of trouble installing updates, I thought it was just traffic. I would repeatedly get errors that it couldn't update. But after repeatedly trying, it finished. But then I couldn't get into the lobby (Error 2002). After TONS of tries, I could occasionally get in, but it would only be for a bit before it crashed. I forwarded ports, updated router drivers and such. Finally I put my old adapter back in (but still using the new router), an old Buffalo adapter, and it works without any issue. BUT that adapter still limits my speed to 20mbps. What is it about the new adapter that's not getting along with XIV? Any ideas?

Thanks in advance.