Unable to update from SMB share (Centos6/7, and Debian 14)

Dear folks,

we are trying to install the linux version of Sophos on some Linux machines, and have ran into a problem with updating.

savupdate.sh failes with:

Can't locate index of \\server\share\SophosUpd\CIDs\S000\savlinux
Failed to replicate from \\server\share\SophosUpd\CIDs\S000\savlinux
Failed to replicate from all update sources

We have traced the issue (after finding https://community.sophos.com/products/endpoint-security-control/f/sophos-endpoint-software/5449/linux-client-not-able-to-update---please-help#pi2151=1)  to the call in uncdownload/uncdownload.sh:

These two calls result in NT_STATUS_LOGON_FAILURE:

 LD_LIBRARY_PATH=../lib64/ ./uncdownload.sh -o /tmp/cidsync.upd -u "domain/user" -p "pass" "//server/share/CIDs/S000/savlinux/cidsync.upd"
 LD_LIBRARY_PATH=../lib64/ ./uncdownload.sh -o /tmp/cidsync.upd -u "domain\\user" -p "pass" "//server/share/CIDs/S000/savlinux/cidsync.upd"

This one succeeds:

LD_LIBRARY_PATH=../lib64/ ./uncdownload.sh -o /tmp/cidsync.upd -w "domain" -u "user" -p "pass" "//server/share/CIDs/S000/savlinux/cidsync.upd"

Sophos uses one of the first two I presume; is there any way for it to use the second one?

We have also tried editing .smb/smb.conf in /opt/sophos-av and adding workgroup=, then setting the SEC console policy to username only, but no success...