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That very much sounds like, for some reason Google has gone from viewing that particular page template as "decent, worthy of rankings" to "ok, will rank if I can't find something better". One thing I am wondering, if you have been hit by this: https://moz.com/blog/google-review-stars-drop-by-14-percent ... which is also related to this: https://webmasters.googleblog.com/2019/09/making-review-rich-results-more-helpful.html Specifically where they say "Self-serving reviews aren't allowed for LocalBusiness and Organization. Reviews that can be perceived as “self-serving” aren't in the best interest of users. We call reviews “self-serving” when a review about entity A is placed on the website of entity A - either directly in their markup or via an embedded 3rd party widget. That’s why, with this change, we’re not going to display review rich results anymore for the schema types LocalBusiness and Organization" It seems as if 'something' existed on your product detail pages which Google was valuing highly, which they no longer value at all. Thus you aren't seeing complete drop-off, but a high correlation between declining (or removed) results and pages utilising that feature Basically self-hosted reviews and some embedded reviews 'no longer count' towards Google rankings (at all). The news broke in September 2019, but I wouldn't be surprised if the roll-out was more recent. Moz posted that they noticed movements on Sept 24, which is very nearly November. As we know, these types of updates tend to slowly crawl across Google's query-spaces, it's not often true that everyone gets hit at once Maybe your site is just in the late batch

Hello Thank you for the detailed, helpful response. I should note that most of our SEO traffic does NOT come from forum pages. The overwhelming amount of natural search traffic we receive is from product detail, category, subcategory, and related (how-to articles etc) pages on the main www.xxxx.com site. I am concerned mainly with the potential fallout of Google seeing 3000 or more 404 pages if we just delete the forum and kill the server, and am looking for the best way to handle that. I am ok with returning a 410 or redirecting anything that tries to hit forum.xxxx.com to www.xxxx.com. What do you think? Thanks

I'm not a 100% sure about it, but probably in specific cases you want to have your own statements for Rogerbot.

Oleg Thank you for the reply. I am going to submit to G as well. What's really interesting is that for some of those ancient pages that have somehow resurfaced, you can view the cache dates.  Those pages seem to have cache dates from late nov and dec 2012. But for others, attempting to view the cached version yields a google 404! IMO, this suggests to its a bug. As an aside, you are certainly correct about canonical and pagination issues on our site. We have implemented canonical thus far only on product pages (over 10k prod pages), and I've had getting next/prev for pagination of subcategories as a top priority for months now. Thanks

Point taken on the multiple H1s on the home page. Good call. Digging deeper into the matter, it appears a backup version of the site was up over the weekend and on monday. It is possible that a different robots.txt file was up. Looking at crawl results for 1/16/2012, Google is showing some really strange things. Thousands of allowed/regularly crawled/.indexed pages are listed as 'URL restricted by robots.txt' for 1/16/2012. We immediately made sure the latest robots.txt file (the one that should be up) had these pages as allowed, and it does, so we made sure that is the one in use. It may or may not have been over the weekend. I resubmitted both regular and mobile sitemaps last night and both are showing with a checkbox today. Hopefully this all sorts itself out in a few days. We certainly can't afford any meaningful long term issues with our natural search visibility. Thank you. Of course, I welcome additional feedback. DMG