Kodi 17.5 (Krypton): exits (crashs) when starting e.g. mp4 movie file

I have a HS 251 and reinstalled it with a new HD and Firmware 4.3.6.1286

I installed then the QnapClub Store and installed Kodi 17.5.

Kodi is starting, but when starting a mp4 movie it justs quit.

This did work before reinstalling everthing.
Some mp4 file are playing, it seems the one with higher resolution causes the problem. Can there be a codec missingß

In the HD Player the mp4 file is played without problems.

What could be the problem here?

I now found a solution:

I installed Hybrid Desk Station 3.2, although this is for the HS 251+ and not the HS 251. But it installed, and so far Kodi does not crash.