I have just tried the link in your post and it takes me straight to the forum, so it is working. This makes me think it is something to do with your own settings, not GN Sorry, I haven't a clue how to sort it, but I'm sure there will be others on GN who can help.
Not sure which section I should post in so thought this might be best. When I get an email notification from GN with links to forum topics and click on the link it goes to : gransnet.cmail20.com/t/d-l-bhkikkt-zljjuqv-r/ I then get the message saying 'cannot open page because it could not connect to server' any ideas ???