Thanks a lot. The package update was the missing part:
Finally I did the following configuration for QNAP NAS Master:
config setprop nut-server User admin
config setprop nut-server Ups qnapups
signal-event nethserver-nut-save
Together with setting the right password in the nethservergui resulting in following configuration:
[root@homeserver1 ups]# config show nut-server
nut-server=service
Device=auto
Model=
Password=123456
TCPPort=3493
Ups=qnapups
User=admin
access=green
status=disabled
[root@homeserver1 ups]# config show nut-monitor
nut-monitor=service
Master=10.0.x.xx
Notify=disabled
status=enabled
and testing seems working as well:
[root@homeserver1 ups]# upsc qnapups@10.0.x.xx
battery.charge: 100
battery.charge.low: 10
.....
.......
[root@homeserver1 ups]#
So issue seems to be solved.
Thank you!