"Access denied by your organization"

I gat that error on a windows defender popup. At the same time I get this error on any browser : ERR_SSL_VERSION_OR_CIPHER_MISMATCH when accessing websites that you would normally block for children or at work (ie the national lottery, or the Tor download site), yet I am on my personal pc, at home, I am the administrator etc etc. A windows technician has logged on remotely tried everything and has made no headway (doing all reg edit adjustments, trying new login profiles etc). I have turned off protections also from my Internet provider. Microsoft says the only solution is to do a custom install again of Windows 11. This pc is less that 2 years old and all updates are on for all software. I do not want to go through the agony of re-installing all apps and passwords etc etc just for this windows defender problem. Does anyone else have any other ideas - windows is depressingly rubbish these days.