Okay ... this is my "simple" configuration on the LE systems (I'm using this since OpenELEC 6.0,1 on my ATV1) ... It fits my requirements ...
I have a autostart.sh in /storage/.config/
#!/bin/sh
rsync --config=/storage/.config/rsyncd.conf --daemon
and ... the rsyncd.conf in /storage/.config/
list = yes
port = 873
log file = /var/log/log.rsync
timeout = 300
[Synology3_Backup]
comment = Synology3 Video Backup
path = /storage/videos/
max connections = 0
read only = false
hosts allow = 192.168.66.251
uid = root
gid = root
... so no rocket technology ...
when the rsync server connects to the rsync client "module" (Synology3_Backup) than it creates a directory inside the module to store the files (/storage/videos/Synology3bak ... Synology3bak = name given by me in the setup of the rsync job on Synology NAS) and its "indexdb (synobkpinfo.db)".
have you tried to create the directory and the file "synobkpinfo.db" in it (maybe an old synobkpinfo.db from LE 9.x copied) ?
This is not really possible ... the "synobkpinfo.db" depends on the job on the server ... means they have a kind of validator (or something like that). Rsync job on rsync server and synobkpinfo.db do need to have the same validator. But if you upgrade from LE 9.2.6 to LE 10.0, the rsync module is marked as valid on rsync server (because indexdb and job do have the same identifier) and it is possible to start the rsync job, but failing because of authentication/authorization issues.
But nevertheless I can manually create folders in /storage/videos/ and place a file there ... no issues from any computer (no need to use root/libreelec credentials).
I'm more thinking in the smb (Samba) implementation on LE 10 ... I know that the support for smb1 is discontinued on most systems, but in LE Configuration smb1 is still available, but nevertheless I doubt that there be a change in the smb implementation starting with 9.95 or so (the configuration in LE Configuration for smb in LE 9.2.6 and LE 10 is exactly the same ...
I'm running multiple rsync jobs from Synology NAS, also to different LibreELEC hosts, but only systems with LE 10.0 fail ...
it seems the second picture is uncomplete.
Sorry, no more options. Just the setting to configure the scheduler ...