Same here. Hetzner found no issues with hardware in diagnostics, they insisted it is related to OS/Software side but on my request they changed hardware which fixed issue.
I Was given the choice between diagnostics and hardware replacement, and decided to do the diagnostics first, which turned out nothing. Decided to reinstall the os and when that didnt fix I was sure it had to be something related to hardware which diagnostics didnt catch. If you have a server mentioned in here and problems turn up, just get the hardware replacement immediately
https://docs.hetzner.com/robot/dedicated-server/general-info...