Wifi connection issues with iOS & MacOS devices only (no issues with Windows, Android, etc)

Since about a week or so all my iOS & MacOS devices (iPhone/iPad/MacBook) are having significant Wifi issues. The wifi connection drops intermittently. After about 30 - 60 seconds the device connects to the wifi again, but sometimes I need to switch the wifi on the device off and on to get a connection again. In a few instances I could not connect to my wifi network at all, and got a message saying “Unable to join the network. This network is operating on Wi-Fi channels in use by several other nearby networks”.

My other devices running on Windows and Android appear to be working without issues.

I have tried everything, including rebooting the router, reinstalling the xFi Pods, deleting my Wifi network from the devices (and adding it back), resetting the iOS devices network settings, and contacting the xFinity help desk (who made me unplug and replug the Coax cable, and who apparently loaded new “boot files”), but none of it worked. All devices have the latest firmware. I have the TG4482A modem/router and 3 xFi pods.

Does anybody have suggestions on how to solve this?