I checked your GP link with the Brave, Chrome, Slimjet, and Firefox browsers. Each browser gave the message highlighted by Pat in reply 71 but then went on to the GP homepage.
Thanks for reply.
About a week ago, I obtained same results as you - first the message then on to the GP homepage.
But since then, I only get the error message on both Chrome (laptop) and Android (phone).
As noted, MS Edge and Firefox works just fine.
I plan to contact GP to see what they say.
Thanks again for the reply post