What would be the purpose of/reason for moving back to a different url? If its been a few years, I’d leave it alone unless you watched everything decline since moving to the main url. Moving the forum to a new url now would probably be a bit chaotic, not only for your main url but for the forum itself…. Only reason I could imagine myself moving the forum in this scenario would be if all those links were really awful and unrelated to the url it currently sits on…
However, if possible, I would like you to expand a bit on your “zombie pages” tip..we run a site where are definitely enough pages to delete (no sessions, no links, probably not even relevant with the main theme of the site, not even important for the architecture of the site)..Nonetheless, I am not very sure what is the best technical decision for these pages…just deleting them from my CMS, redirecting (if there is a relevant alternative) or something else? Unindex them on Search console? what response code they should have? ..

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