On o.S11.4 NX client cannot connect to X server

Hello,
until 2 weeks ago I had o.S11.3 on both my Siemens and Asus laptops.
I have installed NX No Machine. ( I know it’s not open source,I am using the free version).
With commandline ( root) /usr/NX/bin/nxclient I was able to connect to the other machines.
I got Qt: Locales not supported on X server, the NX menu popped up
and I was able to connect by inserting resp codes.

After fresh install of o.S.11.4 on the ASUS the commandline (root) answers:
xlib: connection to":0.0" refused by server
xlib: No protocol specified
nxclient: cannot connect to X server:0.0
The ASUS can still be reached from the other machines (one with o.S.11.3,the third one with o.S.11.2 )
SSH ( Lan)connections are all working forth and back between the machines, even to and from Win XP, however only from Win 7 on the ASUS, but that’s a Win7problem.

Comparing the installed xorg-x11- server-extra : on o.S. 11.3 Additional
X servers ( Xmdx,Xephir,Xnest,Xvfb ) ,on o.S.11.4 the Xvfb is missing, might that be the reason? If not, I’am sorry for the wrong question.
Thanks E.K.

Hello,
eventually having solved my problem to use NX nomachine from o.S-11.4:
commandline: <user@linux-…>:ssh -X <iPnumber>
Password:<user>
Last login:<Date …iPnumber… Have a lot of fun…
<user@linux-…>:su -
Password:<root>
linux-…:~ # /usr/NX/bin/nxclient
after the last input The Nomachine menu pops up and is ready for use.
E.K.