R6400v2 loses internet intermittently ONLY on 2.4 NOT on 5

2.4. WiFi ONLY loses internet several times a day for a few minutes. NOT wired or 5gz.

Also occasionally all devices on 2.4 ONLY say password is incorrect until router is powered off and back on.

Being used as a switch on WoW cable.

Arris DCX3635 gateway modem/router WiFi OFF controls DHCP - off on R6400

Arris port 1 connected to r6400v2 on Ethernet port 1

R6400v2 firmware V1.0.4.106_10.0.80

2.4 and 5 both have different names