That wasn’t as easy as I thought as the even the debugging ssh session is killed in a short time. But I learned how to record ssh sessions and got the kernel messages: https://pastebin.com/NqTDdSMT
I gets interesting below 3504.054370
I think I/O error, dev sda, sector X looks like a faulty SSD, right? Pretty strange that neither a S.M.A.R.T. test nor a read/write test saw that…