Some devices cannot connect to WiFi after 2 days of intermittent issues with broadband

The issues with broadband started on Jan 5 morning. The hub was flashing red, blue, yellow. It was constantly rebooting, etc. WiFi and TV were working badly.

Despite the fact that I received text message from VM this morning (Jan 6) that the issue in my area (SE18 6ED) was resolved, I'm still experiencing issues with WiFi connection.

Some of my mobile phones connect and lose connection every 5 minutes. Sometimes I see error 'could't connect to this network'.

At the same time, a couple of other phones that I haven't used since broadband issue started don't have any issues - their WiFi connection is ok.

My laptops can't connect at all - I see the following issue:  Enter the password 'Some information changed since the last time you connected. We need additional information to complete the connection'.When I enter the password and click connect, I see the same issues.

Note: I've booked engineer visit for Jan 8, but I'd really appreciate it if someone could advise what the issue might be. Thank you.