I don't mind them asking to have one machine connected for some types of problems, but when the issue is COMPLETELY unrelated to the number of machines connected, I think it's stupid. Being refused any sort of support no matter what the problem unless you first connect only one computer and spend 10 minutes rebooting things and verifying network settings, then having them check and find out "oh, yes, we seem to have a problem in your area" is not good customer service.
Specifically what happened is we've been having issues with playing games online lately, since Comcast took over. With one person playing BF1942, it's fine. If another person starts to play, whether on the same server or not, both machines go up to the maximum ping time in the game of 1023ms, and eventually disconnect. This also causes all other connections to fail as well (IRC, AIM, et cetera), and normal pinging latency goes up to the 5 second region. Shutting off one game before they're disconnected lets the other game start working normally again.
I've gone through every possible cause on our side, and it's not us. I've used 3 different gateways, we've tested with both BF1942 and Unreal Tournament (and UT actually has this problem with only ONE computer playing; the net speed setting has to be bumped down below the setting for a 56k modem). I even connected one computer to the cable modem (before trying to talk to Comcast) and started up two games on it and the problem occurred. It doesn't seem to be an issue of there being two machines, but that there are two connections to game servers. And it only happens with games. If there's a heavy download going, ping times go up but not massively. It's also not a bandwidth issue, as it only started recently, worked fine before that, and our bandwidth caps haven't changed (can still upload and download the same).
I used the Comcast/AT&T applet that lets you chat with a support rep rather than sitting on the phone, and couldn't even get her to consider the issue until I had everything set up their way, and I didn't feel like going through all that bull. Aside from that issue, the overall responsiveness of both our connection and the neighbors has gone down. We'd rather pay more money and get a better service.