Mapped Drives Backup

I’ve installed both server and client on the same win server 2012R2 and the setup is as follows:
-Q:\ to W:\ are mapped drives on a FreeNAS
-D:\ is another mapped drive another NAS.
I need to backup the volumes from Q to W on D.
I’m aware of the fact that the system can’t take a snapshot but I’m good with it.
The fact is that even if I have granted the administrator identity to the client service I still get the error about the drives (needless to say that administrator can see these drives).
Here’s a part of the debug just for the first drive.

2018-08-31 17:32:37: ClientService cmd: #IWMRbtOm6l1akJaZeehpI#3START FULL BACKUP group=0&running_jobs=1&sha=528&with_permissions=1&with_scripts=1&with_orig_path=1&with_sequence=1&with_proper_symlinks=1&status_id=13&async=1#token=gvrl5QSP3WnV1soG6lMo
2018-08-31 17:32:37: Async index d5da686479a30dcc7f69c794f2c92af6
2018-08-31 17:32:37: rc=0 hasError=true state=0
2018-08-31 17:32:37: ClientService cmd: #IWMRbtOm6l1akJaZeehpI#WAIT FOR INDEX async_id=d5da686479a30dcc7f69c794f2c92af6#token=gvrl5QSP3WnV1soG6lMo
2018-08-31 17:32:37: Wait for async index d5da686479a30dcc7f69c794f2c92af6
2018-08-31 17:32:37: Removing VSS log data…
2018-08-31 17:32:37: ERROR: Could not open path in os_get_final_path for “Q:”
2018-08-31 17:32:37: Final path: Q:
2018-08-31 17:32:37: Script list at “C:\Program Files\UrBackup\backup_scripts\list.bat” does not exist. Skipping.
2018-08-31 17:32:37: Deleting files… doing full index…
2018-08-31 17:32:37: ClientService cmd: #IWMRbtOm6l1akJaZeehpI#2PING RUNNING pc_done=&status_id=13&speed_bpms=0&total_bytes=-1&done_bytes=0&paused_fb=1#token=gvrl5QSP3WnV1soG6lMo
2018-08-31 17:32:37: ERROR: Could not open path in os_get_final_path for “Q:”
2018-08-31 17:32:37: Final path: Q:
2018-08-31 17:32:37: Removing deleted directories from index…
2018-08-31 17:32:37: ClientService cmd: STATUS DETAIL#pw=idCpOxbnZ9hxiphy47mDkGZ6tO9oxM
2018-08-31 17:32:38: Selected no components to backup
2018-08-31 17:32:38: Creating shadowcopy of “Q” in indexDirs()
2018-08-31 17:32:38: ERROR: Cannot get volume for path “Q:”. Impossibile trovare il file specificato. (code: 2)
2018-08-31 17:32:38: done.
2018-08-31 17:32:38: ERROR: Creating snapshot of “Q” failed.
2018-08-31 17:32:38: Disabling CBT on volume “Q:”
2018-08-31 17:32:38: Indexing “Q”…
2018-08-31 17:32:38: ERROR: Cannot access path to backup: “Q:” Errorcode: 3 - Impossibile trovare il percorso specificato.
2018-08-31 17:32:38: WARNING: Hint: Directory to backup (“Q:”) does not exist. It may have been deleted or renamed. Set the “optional” directory flag if you do not want backups to fail if directories are missing.
2018-08-31 17:32:38: WARNING: Hint: Volume (“Q:”) does not exist. It may currently be not present. If you are trying to backup a network location via mapped network drives please be aware that mapped network drives are per user and the UrBackup client runs as “LOCAL SYSTEM” user per default. See on how to backup network locations
2018-08-31 17:32:38: Script “C:\Program Files\UrBackup\postfileindex.bat” does not exist
2018-08-31 17:32:38: Async index d5da686479a30dcc7f69c794f2c92af6 finished with “error - index error”

Any suggestion?

See here for the workaround