Private Wifi keeps dropping signal

Our business private wifi keeps dropping its signal and even when it is up some devices are not able to connect.

I would also like to turn off the public XfinityWifi. If the Business private wifi keeps dropping, I would like to turn that off too and use our own wireless router.

I have unplugged the Comcast gateway and made sure everyone else disconnected and reconnected their wireless devices, but that has not helped. 

I can't keep disrupting everyone trying to get some work done even though the poor service continues to cause disruption.