For months I couldn't work out why my A4 Chip devices (iPad & iPhone 4) were so slow on my router, compared to my 3GS and everything else.* It turns out that the issue is linked to the router's 802.11N setting. For some reason, the A4 chip devices connect way slower on N that they do with b/g on this particular router. I changed the router settings down to b/g and I now have full speed wifi once more! I lost the page where I found the tips. I'll find it when I get home.