Hi,
you would need set some specific values on your Synology https://dietpi.com/forum/t/move-user-data-on-nfs-drive/4953/1
as well a similar question https://github.com/MichaIng/DietPi/issues/4301
Personally I tested it this week
Yes SAMBA is not supported as SAMBA did not support file system permissions and sym links