I'm having great difficulty maintaining a constant network in my home, and I suspect it is because the router and extenders are sitting on the same radio channels.

System as follows. 

BE9700 tri-band acting as router with 2GB cable service. 

2 x Re705X Extender

1x RE550 extender

Each router is assigned its own SSID name, so I can be sure devices are connecting to the correct extender/router. 

I am heavily dependent on home security and smart home kit, I have around 20 security cameras (2.5ghz and 5ghz) and many other wifi/matter devices and hubs with around 70+ dimmers/lamps/sensors/Apple TV spread around two floors and out into a large garden. 

So I have a mix of low bandwidth high bandwidth devices.

The network devices are frequently dropping out and changing I.P addresses, so I have turned the DHCP server 'off' for the extenders and manually assign each device with its own I.P. 

However, no matter how hard I try, the extenders seem to (more often than not), choose the same radio channel, so when I am trying to log into a certain wifi SSID my iphone will refuse and say there are too many devises using the same radio channel. 

I have confirmed that even after rebooting at least 2 of the three inadvertently choose the same radio channel.

I dont see anywhere in the admin page a section(s) where I can manually pick the radio channels to avoid them stamping over each other.

 

Is there a way to do this?

Thanks.