Sudden decline in new registrations

[MegaBrutal]

I run the forum linked in my profile, providing community for neurodivergent people since 2012. Sadly, we've been already experiencing a steady decline in the recent years, starting from around 2017 we have less and less active members, still we were running with great topics and in person meetups. There is also a Facebook group with the same theme and goals which skyrocketed in popularity and newly diagnosed people are more likely to find that and settle there instead of joining our site. Up until recently, however, we were still getting new registrations at a nearly constant rate, around 2 people monthly (how many of them actually stay is another question).

This January, I upgraded the former SMF 2.0 to 2.1. With this, I also needed to drop the former and familiar Losox Theme, because it was not compatible with 2.1 (and wasn't even responsive, which was a great complaint we were getting over the years). Upon testing, I chose the Ubuntu theme, partly due to my sentiments towards the Ubuntu operating system.

In the past 3 months we got 0 registrations, unprecedented in the 12,5 years history of the forum. I'm trying to find the reasons. I think SMF 2.1 is objectively better in almost every way (aside from some bugs and the incomplete translation): mobile friendly, supports drafts, has likes, mentions, can quote selected texts – these are formidable quality of life features. Maybe potential users don't like the new theme, or something's wrong with our SEO, or maybe 2025 is the year where the people of the internet finally decided to leave forums for good, or maybe search engines (especially Google) changed their indexing policies to kill self-hosted community sites. Maybe our most recent article is too depressing.

Do you have any ideas? Do others experience the same? After all, I'm puzzled that the recent improvements not only didn't bring more new members, but a sudden drop. I'm trying to figure what we could do about it, whether it's a change in the site or a global change that disfavors forums in general. I know it is a huge disadvantage to require people to register before they see the boards, but unfortunately I can't change that due to historical reasons – though it's been like this for more than a decade, it can't be the reason for the recent decline.

[vbgamer45]

I would first check that you can register yourself create a new account and see if the process works.

[shawnb61]

I've seen similar dropoffs upon major site changes, e.g., when I cutover to https, 2.1 upgrade, or moved hosts. 

It's almost like Google saw a massive change &  wasn't sure it was real or temporary or in error, and we fell in search rankings.  And, like it or not, folks are generally finding you via Google.

So...  I'd go in to Google Search Console & check things out.  I'd evaluate any errors for action.  If things look good, submit pages for crawling.  Submit your most recent topics & the board index.

If you have a LOT of content, then a sitemap really helps them find the latest updates quickly, rather than having to recrawl everything to find new content...  Submit the sitemap in Google Search Console.  It really does help get your new content on Google immediately.

Submitting links for indexing is a pretty easy way to bump your search ranking.  It reminds Google you're still there.

Warning:  If Google decides your site needs a recrawl, they may pummel your site for a couple weeks.  In the past, you could control the crawl rate, but they removed that option.  You just gotta deal with it...  Fine tuning your robots.txt helps, make sure they're not trying to index meaningless links (like message-level links).  Keep an eye on the crawl errors in the console.