Thank goodness we're back. That was a sad couple of days.
Side note, there doesn't seem to be any way to contact anyone responsible for this instance. I scoured sdf.org and saw that other apps / pages were working but there was no way to raise awareness of the issue. That seems problematic. Can we please get a support form or generic email address for such moments?
I've tried to hit support for the Lemmy instance and the Peertube instance - and for the Matrix instance too - both through forms, emails and in the support chat thing in the shell account. Nobody answers, ever. It's like crickets in here.
The only email address that answers and provides help is membership@sdf.org.
There's also going to https://sdf.org/?subscribe, scrolling to the 2nd from the bottom row "Support SDF's efforts in the fediverse", and use that form to send them money specifically to support the fediverse services. If they get more money for the fediverse, they'll pay more attention to the needs of the fediverse. Right now they're more focused on migrating to a new array for their MetaARPA subscribers.
In the past, SDF has been rate-limited by Let's Encrypt due to requesting a large number of certificates, which means renewals sometimes take a day or two or more. It's not ideal, but it is what it is.
Maybe they need to start staggering their renewals so all the fediverse servers don't expire at once.
I wasn't able to do that even, Firefox with HSTS is dumb and goes against user freedom by failing to give a meaningful bypass method. Though I was able to get around it.
FYI people won't tell you how to disable HSTS enforcement, just delete the contents of the file SiteSecurityServiceState.txt then set permissions of it to read only and owned by root for good measure. Then the unbypassable warnings are able to be bypassed same as any other http warning on an https site.