RayL12 wrote:

All the wifi of routers everywhere share just 16 frequency bands.

14 channels at 2.4GHz, of which 13 are legal in the UK and one of those
tends to have patchy support.

By default, all sending gear and receiving gear is defaulted to band
7.

Not IME, channels 1,6,11 are the common bands as they don't overlap.

If you change the band, you must do on all your other devices in &
out.

Not so, if you change the channel on the access point/router, all
connected clients will quickly follow it to the new channel, without any
reconfiguration.

However, you will be more or less garaunteed a full band to your self as
no one else ever changes from the default.

Many routers automatically and continuously select the "best" frequency.

If your Wifi is under such stress already, the bluetooth may be the
tipping point.

Bluetooth uses spread spectrum frequency hopping on a larger number of
narrower channels, an attempt to avoid interference from other devices
(e.g. WiFi) sharing the 2.4GHz band.

Wouldn't surprise me to find interference between bluetooth and wifi
devices in a particular situation, does surprise me it crashes the
router so repeatably.

Plusnet do have some Thomson firmware on their community website, if
that didn't help I'd buy or scrounge a router from someone.