The password and network name for your old dsl connection are not the same as Fios
on your tv under the settings you can go into WiFi and look for the Fios ssid name that is on the router. You select it and use the password for that network which is on the Fios router.
there are 4 LAN ports on the Fios quantum router. I have found if you can run ethernet cable from the smart tv to the router it’s a faster and more stable connection than WiFi