I've had the benefit of FIOS high-speed net access at home for a few years now, and have been thrilled with the reliability and speed. A few months back, however, the Verizon-provided router died. So I purchased a WNR3500 Gigagbit Router as a replacement.
While this router worked quite well for almost everything, there was one annoying problem: I couldn't reliably login to iChat (using a MobileMe AIM account). Sometimes it would work, but more often than not, it would connect then disconnect rapidly, over and over again, leading to a message from AIM stating I'd attempted to login too many times, and I'd have to wait a while before trying again.
After much searching, and with some help from the Mac OS X Hints readership, I found this Apple support document, which perfectly described my problem. Thankfully, the fix provided there also works perfectly--just change the AIM server port (in iChat's preferences) to 443, the port for https connections. Make sure you're logged out of iChat, then go to Accounts -> Server Settings, and change the port from whatever it is (5190) to 443, then close iChat's preferences. (You'll need to make this same change on any Mac on your network, of course.)
I'm not sure what's going on with the Netgear and the default port; it may be related to some of the firewall features in the router, but I really don't know. In any event, this change fixed the problem--iChat is now fully functional. If you're running into the repeated login/logout issue with iChat, more than likely, a simple port change will fix the problem.
This story, "Solve an IChat Login Issue on Certain Routers" was originally published by Macworld.