No apps work / can be installed / deleted after Firmware re-install

Hi everbody,

due to a forgotten password I followed the advice to reinstall Os 6.6.1. This actually worked well and I was able to set a new password. 

But something must have gone wrong, as I now have intensive problems with my apps.

1. Apps, like plex, won't start, but also can't be deleted.

2. New apps can't be installed.

3. The available apps list itself can not be retrieved from the netgear server.

Of course I tried to to restart the NAS several times and also tried to switch it of entirely and wait for some time. I also tried to re-install the OS several times without success.

Does anyone have an idea what I might do?

Thanks 

Christian