It seems that my TZ300 is blocking my being able to log into to sophos.com. The login to Sophos works fine until I get redirected to sophos.okta.com This then hangs. If I bypass the firewall I can log in fine. I have added okta.com to the allowed section in:-
Security Services/Content Filter/Configure/Custom List/Allowed URI
... but it makes no difference. I can't see anything on the TZ300 log. I have also filtered packet filtering for my machine and can't see anything that would help me resolve what's going on.