Instances marked down and showing wrong TLS grade despite being up (inconsistent UP/DOWN state)

[b2cc]

Hello!

We manage a couple of instances on our private infrastructure and got reports from Fedilab users that seem to rely on your service, that some of our instances are "DOWN"despite being up and running.

instances.social marked some instances "DOWN" and being shown with an TLS rating of "E", despite them being up and getting an "A+" when I manually run the Qualsys SSLTester.

Affected instances include:

climatejustice.global
climatejustice.social
climatescienc.es
fedi.at
indiepop.band
mental.camp
mtg.garden
wien.rocks

For reference: despite being on the same infra, the following instances are shown as "UP" (correctly).

climatejustice.rocks
social.fairphone.community
tyrol.social

Could you look into this?

Also, from which IPs are the check being run? Would be nice to know, then we could specifically whitelist them on our firewall.

Thanks for the help and all the best!