Some devices not connecting to Wifi

I've had an XB5 Gateway for a little over a month now and I am starting to notice some problems with it.  The main issue is that some devices won't connect to the wifi network.  All of these devices connected fine to my old network using an older Arris Xfinity gateway in bridge to an airport extreme.  There are two Smart TVs, a Samsung and Vizio that just won't connect.  I also have a Smart Scale that is hit or miss, and an older Apple watch series 3 that won't connect reliably.  Either the devices say "incorrect password" which is not true or "cannot connect."  My network is combined 2.4 and 5, and it is the same SSID and password as previoous setup.  I have tried forgetting devices from xFi app (which doesn't accuratley show devices that are online to begin with) rebooting modem and resetting TVs and scale.  After the last reboot, the Vizio TV now connects, but the Samsung won't.  The devices are literally 3 feet away from the gateway.  Does anyone have any suggestions?