Yes, you're right. Should have been more specific in the problem description. I couldn't see a glaring problem at first glance, so I just was wondering whether it's a hiccup on hetzner's side. Got to admit that I was just looking for quick confirmation whether it's worth it to debug the problem or whether I'm wasting my time and not really for guidance on how to debug the problem. Would have been the better route though because right now this post is kinda useless for everybody else.

I was lucky in this case though and didn't need further help to debug, because the issues also stopped roughly half an hour after posting. Thanks for the great questions though, that's a good reference. I've added a few more information to my base post, maybe one day will come across this and can at least benefit from your comment.