Oh, yeah, forgot to specify — there's a couple of issues on github of people having the exact same problem (mostly with off-the-shelf Mastodon servers rather than homebrew), over several years, and with no obvious resolution in sight. My website gets an "A" on SSL Labs, and I don't know how to look any further because Mastodon doesn't tell me anything useful.
Wasn't the Fediverse supposed to be about encouraging people to do their own stuff? 🤔
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