HG633 wifierrors

I recently upgraded to fibre and received a hg633.
I used to use a netgear which was great but is not vdsl.

I now get numerous reconnects, laggy wifi and millions of errors on the stats.

The range of the wifi seems great on first glance but drops down at random intervals.

The modem side is fine and the lan side is fine. My problem is just on wifi.

The router is in exactly the same place as the old one. No interference.

I have changed the bands. No help.

It happens on 2.5 and 5.

There is obviously a problem with the wifi on some of these models judging by past posts. Could you please
Send me a replacement for testing. Preferably a different model if possible.

Thanks
James