Hello,
I had the same issue while installing the adaptor at a customers house. I even defaulted the router since the customer enabled all kinds of security features. I still was not able to get it to work. I even did port forwarding like tech support from voipo told me to do and it still did not work. I was on the phone with Belkin and they had no idea why their router was blocking the adaptor. They tried to blame the adaptor and said it must be bad. I pulled the router out and installed a netgear router. It has been working ever since. There must be a default setting that has a rule that is causing the problem and even if you find it the setting may leave you with out some kind of security or function you may or may not need. My suggestion is to return the router and get a netgear, or linksys router. I gave the belkin to a IT friend of mine and he is still trying to get it to work for future installs.