There has been some network issues since yesterday that were out of my control. I reached out to Hetzner but didn't hear back yet. However, it looks like the issue is gone now.
Unfortunately the issue has returned and Hetzner's support has not been responsive at all, I'm quite disappointed. I have taken the matter into my own hands and I have migrated the server (recreated another VM from snapshot). This seems to have fixed the issue, hopefully for good 👍