Repo storage is "1&1 Online-Speicher" (https://www.1und1.de/sd2) mounted via davfs2, which has worked quite well over the last years. Borg repo is a subfolder in this ...
When creating a hard link to a new symlink, a spurious "Input/output error" (EIO) is often returned, probably due to a race condition / cache inconsistency issue in VirtioFS. $ docker run --rm -it -v ...