How do i attach an extension to a SPA2102

[Riverplaceobg1]

I have a SPA2102 and Had to Reset the password for my main router . Now i am unable to get calls to my phone router that has an extension

[Dan Lukes]

SPA2102 need no password to send packets to just router.

Please describe your environment. What's the relationship between "router" and SPA2102 ? Are you running call manager or so on the router ?