I did a little poking around viewing the page sources for the new forum, and I am suspecting that this forum is now a WordPress “bbPress” site. If that’s true, then there are a number of converters from phpBB (old format) to bbPress. Here are some links:

• https://wpmudev.com/blog/how-to-migrate-a-phpbb-forum-to-wordpress-and-bbpress/
• https://bbpress.org/forums/topic/phpbb-to-bbpress-converter-and-best-practice/
• https://bbpress.org/forums/topic/bbpress-vs-phpbb/
• https://bbpress.org/forums/topic/introducing-bbconverter-convert-your-current-forums-for-use-with-bbpress-2x/page/8/
• https://bbpress.org/forums/topic/a-phpbb-to-bbpress-database-converter/
• https://www.webnots.com/comparison-of-bbpress-vs-phpbb-forums/
• https://www.helloari.com/blog/2011/04/wordpress-forum-tools-bbpress-vs-phpbb-comparison/

But I tend to agree with Eric that it might be easier just to let the previous forum live on in a “read only” state to preserve the history. Is there any reason that couldn’t be done?

If it’s a matter of workload, I am sure you will find some volunteers. I’ve been managing the US Hawks site (phpBB) for nearly 14 years now, and I could lend a hand. If nothing else, you could reactivate the old site just long enough to run a site-scraper to capture it all as static HTML pages. You could host those static pages anywhere in your current site. It would be better than nothing.

Most importantly, please don’t lose the history that has been built here for well over a decade.

Thanks.