This network is operating on Wi-Fi channels in use by several other nearby networks.

Continuously getting this message. 

“This network is operating on Wi-Fi channels in use by several other nearby networks”

Sometimes my network will appear on devices without the lock on it. 
I have called and don’t online support. They say I have too many devices for a home network. I currently have 8 -several of which say are connected but won’t actually work (security camera, printer, thermostat- can’t get those to work). Sometimes the iPads won’t connect and our phones are frequently not connected- we just don’t notice it as often since we have data. 

I have tried the suggest troubleshooting on other posts to go online in the wifi settings and deactivate the 5ghz then reactivate. That didn’t work. 

please help!