Just tried another laptop, same problem, PPRuNe is inaccessible using Firefox if I don't use a VPN and try and spoof my location as being outwith the EU. No problem when using Palemoon, but the problem seems to also be there with Chromium (the fully open source version of Chrome).
I've tried blocking cookies, makes no difference, it seems that there's something fundamentally broken within the Trustarc GDPR compliance feature, and from the fact that this only started happening this afternoon (BST) it looks rather as if it might be related to an update, perhaps. There's been no update to any of the browsers I've been using today.
Definitely not an obvious cookie problem, as I've cleared all cookies, the cache etc. The problem seems to be the Trustarc script hanging, part way through execution, with some browsers not behaving as the Trustarc script expects.