Gaming lag from Vonage

Ok first off here's my setup: Cable Modem--> Vonage modem--> Belkin Pre-N wireless router--> PC

With this setup I get a tremendous amount of Lag in games. Additionally my internet also flickers off and then re-connects immediately. As you can imagine this can range from aggravating when i get disconnected from a WC3 game, annoying during a TF2 game and completely unworkable with something like online poker. Whenever I connect my PC directly into the modem i have no problems. Whenever I put the Vonage behind the router the phone connection is miserable and usless. I am desperate, can anyone think of a configuration/ internal settings that might fix my lag problem?