I experienced also failed backups yesterday, XOCE 5.82.1 / 5.87.0
"message": "connect ECONNREFUSED 192.168.20.71:443",
"stack": "Error: connect ECONNREFUSED 192.168.20.71:443\n at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1148:16)\n at TCPConnectWrap.callbackTrampoline (internal/async_hooks.js:131:17)"
First suspected the xcp-ng updates but I have had successfull backups after installing the patches so ruled that out.
I also had updated XOCE this week, so started looking into that.
Did an update to the current version of XOCE 5.82.2 / 5.87.0 and backups are working again.
Only thing I did not figure out right away; how to kill the still active tasks from the failed backup jobs? But a restart of the toolstack on the xcp-ng server fixed that as well
Of course after all the troubleshooting I went to the forum and found this topic. Should have done that first thing