New modem password, doorbell easy, floodlight cam, not connecting to temp broadcast

T-Mobile had us change our password, and we now have to update our ring and blink devices, as well as every other wifi device . The doorbell is 20 feet from the floodlight camera. It was easy peasy. It broadcast a temp signal and was set up in minutes. I held down the button on the floodlight cam for 20 sec, flashing light, voice set it was in set up mode..... it said connect to a temp signal, failed. tried again.. and again... no connecting. Doorbell is older than the floodlight cam. re booted the modem. rebooting again.. again... hit the camera button again... The T-mobile modem worked with the floodlight cam prior to changing the passwords just fine for 4 mos. Excellent signal, faster than the old xfiinty modem. Now we cannot get the floodlight cam to connect. When I go into the wifi signals on my iPhone, I don't see any temp signals. The modem is 2.4 / 5 dual band.