How did you set up the FF sync server? I just did a quick search and I think the instructions I've found were mostly outdated. Do you have a link or a name for the port?

I also enjoyed hetzner for a while and if I'd want a ZFS install I'd probably go with them as it's definitely very nice how they do it. But as I've just previously commented I found a slightly better price for my minimum needs with vultr.com (5$/per month) and ZFS is not important to me on this box.