How to contact a Lemmy instance administrator if server seems to be down?

The instance feddit.nl (a Dutch Lemmy instance hosting the largest Dutch communities AFAIK) appears to be down. None of the communities can be accessed anymore.

It made me wonder if the current system of Lemmy/Mastodon decentralized servers isn’t too weak with regard to continuity. I don’t know what’s going on with feddit.nl, but if the administrator doesn’t respond to an issue, hundreds or thousands of users can be cut off from the fediverse without them being able to do anything about it.

And what if an administrator suddenly decides to quit, go on holiday, falls ill etc.?

Does anybody know how one can contact a Lemmy administrator in cases like this?

But also: how do you know if an instance is stable enough to rely on?

Shouldn’t there be some kind of backup, where administrators can contact each other in case of some problem?

And what happens to the communities and content if an administrator permanently shuts down an instance?