Some update
Before sending my Samsung to service I was able to flush it completely and restore system to factory (there is nothing to lose ).
After restoring, I've done all maintenance tasks like installation of anti virus and complete actualization (windows 8). Additionally removed with 'Programs and functions' some Samsung pre installed apps (Norton, player stuff, helpdesk etc) BUT leaved all drivers in peace (even not running SW update).
Now it works much better - about 1 hang on hour (37 db signal 10 cm from router). Maybe this is a clue - you must have exact and only driver version because - like with 16.1 version - some parts of package can be downgraded or upgraded. Maybe some parts or registry entries stays even after driver remove. So basically you can never clean driver garbage and got one chance only...
I don't believe in miracle - this solution probably resolve only 1% of problems and - as you see above - it is not 100%.
I will update this later with exact version number that came with my system.
Cheers
[UPDATE]
Preinstalled by samsung intel driver version is 15.5.6.48
And what is also important there are 3 intel ProSet components:
Intel PROSet/Wireless for Bluetooth(R) + high speed v15.5.4.0423
Intel PROSet/Wireless for Bluetooth(R) Technology v2.6.1209.0268
Intel PROSet/Wireless WiFi Software v15.05.6000.1620
It works almost fine (tested for about 5 hours only one disconnection in that time)