Wifi Channel problem

Hi,

I had a new HUB router delivered last week as the old one was faulty.

Now I find that if I set a WIFI channel, it changes itself to something else after a short while to a channel that is conjested.

For example I set 2.4ghz to channel 1 and saved settings, an 1hr later it has moved to channel 6 !

Getting same with 5ghz, I set it to channel 48 and it moves to 44!

Please help, as this new router seems faulty.

Thanks