Is this still a problem for you?
I don't have a Microsoft environment with which to test, but my Firefox view of content at the given URL
https://forums.macrumors.com/forums/alternatives-to-ios-and-ios-devices.157 – note, the absence of a trailing
/ – does
not include the word
Expires so my first guess would be, an intermittent problem involving your browser's use of
cookies.