Not sure if this is the right venue, but here goes: New Xfinity/Comcast install at my girlfriend's house a month ago, moving from Century Link/Driect TV due to satellite problems. Wifi works fine on her old hp windows notebook (that I just reformatted myself). In OS X SL I can see the network, so I input the correct WPA password and quickly get a "connection timeout". (I can connect via ethernet without a problem, but that would require running a really long cable to my office, two floors up.) I boot into Windows 7 via bootcamp. Same basic story. No luck through Ubuntu either. I can connect to the neighbors' unprotected Century Link DSL just fine (albeit slow). In fact, I almost never have problems connecting anywhere with my Mac, including Verizon FIOS at my old apartment, also with WPA encryption. I've checked all kinds of settings. All seem correct. I've tried DHCP and Manual. I've gone into her router settings, and I can't see anything weird there. I've found a few references on the web, but they don't seem applicable or recent. Has anybody else encountered this? Is this a known Xfinity vs. Mac problem? Yes, if nobody here has an answer, I'll be calling the X folk soon.