I wish I knew more about Vonage. I know what it is but not exactly how it works.

That said, many cordless phones use a wireless frequency that can interfere with wireless routers. When you use Vonage, do you generally use a cordless phone? If so, that phone may operate at the same 2.4 GHz frequency that WiFi (the connection for the wireless router) uses.

I may be showing my ignorance of Vonage by writing that! All I can say is that lots of cordless phones interfere with wireless routers. I specifically bought a cordless phone that operates at 5.8 GHz, just so it wouldn't interfere with my wireless router.

--Bob