@olivierlambert I feel like the cause of the timeout is what I posted here: https://xcp-ng.org/forum/post/107454
The incidents of the errors in syslog correspond by matching pool, date and time to the incidents of errors in XO backup. I've traced through several of these incidents in the syslog and matched them to the errors in the XO metadata backup and matched these to missing metadata backup files in the directory on the storage server (ex. 20260807T041000Z) which is created even if the backup fails.
I would look in older logs to see if maybe this has been happening for a long time, possibly before an XO update now shows the error, but my syslog data only goes back 30 days. The XO metadata backup errors started over 30 days.