how to bypass "No route found for GET/ucp.php

[peval72]

Dear All
i have both a Windows 7 PC and a Macbook Pro with touch-bar, and with the first i can log into the VLC forum whereas with the second i get the above message, regardless if i try logging in with Safari, Firefox or Chrome
How can i just login to the forum?

I read some other posts but i could just read some flames but no solution
Is there a solution?
Many thanks
Paolo