Thanks Lawk. The providers were here and separated the 2 bands, and the iPad worked fine. Providers then decied to merge again - no idea as to why, and so iPad back to not able to join.
Also discovered that wifi printer will not get onto wifi, so as second best have had no choice but to hard-wire, which is not ideal. That comes from changing from a provider where all worked fine, but not too fast, to one with fast fibre! Oh well ...........
Thanks again to all who have tried to help me resolve this matter; really appreciate your efforts.