Well, I returned the unit and got an S6500 in the hopes that a higher end unit might be better. Same problems connecting to the internet via Airport (connects to Airport, just not the 'net). I am able to connect to the internet via the Comcast router, and it hasn't booted me off yet, but I'm not very confident since there's not good reason that Airport wouldn't work (again, works fine with my 5 year old S580).Sounds faulty. The last few years Sony's have been great with internet for me.
I'm curious about the IPv6 possibilities. It didn't do anything for me, but I'm wondering if that may lead to a solution.