Exchange restore fails - old server no longer exists as part of DAG

Hi,

I am attempting to restore an Exchange 2016 database and log files to an alternate location as flat files. I have previously done this without issue, and tested with another database successfully today, however the server where this mailbox database was backed up from no longer exists and is no longer part of the DAG. The backup fails with the following error:

V-79-57344-65072 - Connection to the restore target has been lost. Operation canceled.

It seems like the restore job is trying to connect to or check for the original server which was a member of the DAG at the time of the backup that no longer exists as I get the exception in the job log below:

The Backup Exec server was unable to connect to the Remote Agent on machine (Machine name removed by me)

Any ideas on why this is happening?