With xxx.xxx.xxx.xxx being the ip address of your SLP DA, does

slptool -u xxx.xxx.xxx.xxx findsrvs service:smdr.novell

list an entry for each and every physical and virtual NCP server object, including the "culprit one"?

Yes i have an entry for every ressources and also physical server

Do you have something (better: do you have smdr) listening on port 40193 for the resource ip address, i.e.
what do you get on something like "telnet xx.xx.xx.xx 40193" when you issue the command from the host you want to start nbackup?

telnet command works

ss -laputn |grep 40193 show tcp listen on all ip ressources

To summarize:

if you run the nbackup command against the culprit resource from the server hosting the resource, it doesn't even ask for a password

if you run it against any other resource or the address of the host itself, you get a password prompt

correct?

Yes. This is correct. When the password is prompt, i enter the root password and the nbackup work ; so miggui on this ressource.

Do you also get something like "nbackup: Unable to retrieve the Target Service Name list" along with "nbackup: Connection denied"?

Have you ever tried passing the password on the command line with "-P" ?

No, i have directly connection denied. I have also try the -P to pass the root password but same error message

Does it behave differently with another user, e.g.

/opt/novell/sms/bin/nbackup -U admin -R xxx.xxx.xxx.xxx -cf /tmp/migsrc.sidf /etc/os-release

This would require "admin" to be LUM-enabled (id admin) and with rights to create the backup file (that's why i suggested /tmp).

You might get more information by enabling debug logs by uncommenting SMSDEBUG and SMSDEBUG2 in both smdrd.conf and tsafs.conf (in the folder: /etc/opt/novell/sms/) as shown below and restarting novell-smdrd.service.

#
SMSDEBUG: fffffffc
#
SMSDEBUG2: ffffdffc
#

The debug logs (smdrd_debug_*.log and tsafs_debug_*.log) will be available at /var/opt/novell/log/sms/ folder.

On the node where the RESOURCE is currently running, enable SMS debug logging and run the 'nbackup' (/opt/novell/sms/bin/nbackup -U root -R RESOURCEIP -cf /tmp/migsrc.sidf /etc/os-release).

After the test disable the debug logging (comment out SMSDEBUG and SMSDEBUG2 in smdrd.conf and tsafs.conf and restart novell-smdrd.service).