Try RCN since they installed them. I'm guessing you rented them from RCN?
Do you have access to a different brand router (a friend's?) to test? Maybe it's a Belkin problem? Wouldn't be the first time...Thanks, I'll check. Don't know if I have a firewall on Belkin router, but I likely do, since it's protected with WAP. But I disabled the protection and it still didn't work.