Sorry to post in this thread again, but this has been a massive issue yet again recently after joining and using a new forum for the last few weeks.
Frequently in the evenings I've been reading very long threads, and searching product codes a lot on this new site on my phone and the lack of navigation at the top of the page results in an awfully frustrating user experience.
Many of the very long threads discuss products, and the first few posts of each threads are review content, so it's not unusual to need to jump back to the first post to reference information, check some tech specs, find a video etc. This is a pain if you're anywhere but the first page, as you then have to scroll all the way to the bottom to navigate back to page one.
It's a massive issue when arriving on a post from search results too, whether it's internal search or google search. You land at any post past page one, especially if it's near the top of the page and to find context or go to the 1st post to read the review or OP you have to swipe swipe swipe to get to the bottom of the page to find the navigation and go back.
It's so frustrating.