NAS server denies access unless manual

Running Acronis Cyber Protect Home Office Build 39703 (current version). I am trying to backup a Windows disk over home network to NAS server on which I am running Ubuntu. When I first create the backup, I can browse to the disc just fine. I create and test the connection just fine using the username and password for the account on the remote Ubuntu server, the connection tests OK, and the backup runs to successful completion. However, on all subsequent automated backups, they fail with the error message "Access is Denied". I am guessing that for some reason Acronis is not caching the access information when I first create the backup. Has anyone run into this problem before? Does anyone know what to do? The older version of Acronis used to require me to edit the username and password into the URL for the server, and that worked OK, but that option seems gone in the new Acronis.
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