Instaling the latest patches for NPVR 3.2.9, including the NPVR Samsung app patch n 8 fixed the problem (
Luckily I found the fix via this thread ( I'm not sure which thread is the best place to keep track of this problem as it's on 3 places but just to make sure I've posted my comments here.

There is still a small problem with the time server settings on the EPG listings but I'll reply on that via this thread (

So finally the NPVR Samsung client app is working again (thanks sub). Great!
PS: Hopefully some day the aspect/ratio (yellow button) gets fixed to.