1809 wifi not working after update to 1903 failed then rollback

Asus Vivotab Note 8 (M80TA) tablets:
Atom CPU Z3740 1.33 GHz processors

I have 2 machines: 1 x 32gb and 1 x 64gb. Machines are otherwise identical.

Going from a start-point where both machines worked perfectly on 1809.

On the 64gb machine 1903 installed with no problems.

On the 32gb machine the update failed and reverted to 1809.
Now the machine won't show wireless networks . Bluetooth works but is Jerky/spasmodic.

The Asus website is not showing new drivers for wifi or bluetooth. Anyway the 64gb machine, with the same drivers is working fine.

I have tried the following:
sfc: only Defender faults shown. (I can't do DISM because I don't have wifi.)
Reset Network drivers
Uninstalll wifi and bluetooth drivers and restart
Uninstall wifi and bluetooth drivers and reinstall manually
clean install 1809
clean install 1903

After clean installing either version everything works perfectly except wifi (and bluetooth spasmodic)

Repeat:
1. Both machines have the same wifi and bluetooth drivers
2. The faulty machine was working fine at the start of the 1903 update. The update failed due to lack of space. (Windows did not ask for USB stick or more space).
3. Rollback to 1809 took place. On restart many things were problematic. Had to reinstall wifi, bluetooth, SOC and ATK drivers manually. Wifi was not working after rollback. Bluetooth spasmodic.
4. Wifi now shows: 'No wifi networks found.'

Any help would be gratefully received.

Any ideas on the above?

Thanks but that isn't the solution.
I have lots of other devices using the router. Reseting the BIOS (the latest version is installed) does not change things.