Changing the modem to bridge mode seems unlikely to help unless there's another router behind the modem that's taking care of authentication instead. The kind of intermittent "on-off" results you're describing sound more like a broken authentication server over on Verizon's end.
If you want to know if its on your end, go into your modem page and look at the IP address. If it begins with a 10.xxx.xxx.xx , then it's a wrong PW on your side. If its 70.xxx.xxx.xx or 64.xxx.xx.xx or whatever your range is then it may very well be Vz problem. Penewah!
