Join game in battlelog. It'll launch origin and you'll get login error. Type your pass and login. it'll log you in offline mode. Now retry joining server.
Disable UPnP in modem settings. If you have already disabled it and still face disconnection then turn off the modem for few seconds and turn it back on.
Belkin Surge Protector has lifetime replacement warranty. I had mine replaced with a new one, no questions asked. But, I got it replaced at the shop I bought it from.
Try repairing your install for lag issues. Fixed it for me, twice. Both times my game crashed while changing in-game video settings, thereafter I faced lag issues but repairing install did the trick.