I’ve given up on comcast fixing their IP lease time issues, I am still seeing very short lease times a week+ later.
I have found that my old sonicwall firewall was particularly perturbed by these short leases, so i replaced it with a Linksys WRV54G that I had purchased a while ago. No amount of coercion could make it work with the xbox tho — i tried port forwarding, turning on and off upnp, assigning the xbox a static ip and putting it into the dmz, etc. Just never clicked.
So I printed out Microsoft’s advice on compatible routers and trundled off to Fry’s this AM. Ha ha ha ha ha ha. Microsoft’s list is very stale, not a single router with these model numbers is actually for sale anymore. So i picked up a dlink DI-704UP — I know dlink has great market share, and the number was similar to a router that was supposed to be compatible. Works fine.