SamyGO

Restart Smart Hub shows this screen: After more than 30 minutes smart hub is also empty as after factory reset and also with tried more than one restart of the tv...

Possible you have to setup Smarthub country, check wiki for how-to.

You mean this one?
https://wiki.samygo.tv/index.php5?title ... n_F_series

No, just above
https://wiki.samygo.tv/index.php5?title ... _Smart_Hub

Thank you. I have done this and got the list to select for country code.
I then have selected my country "Deutschland" but then in the next screen the same error dialog as in step 9...

Internet is available because if I insert the "rooting" usb device and connect with telnet I can ping internet addresses:

additional info...
after inserting the root usb device I got additional apps displayed...

...not sure but it seems that Smart Hub now is only available and working with rooted device...
Removing the rooting usb stick and trying to start the "samsung apps" app results into a black screen...

Could it be that the apps showing are coming from the "root usb device"?

If the mentioned apps are SamyGO-something it's likely yes
About original problem, no more idea on my side, maybe somebody else

not sure if one of this would help, but:
1. could a firmware update (same version for example) solve this problem?
2. is there a way to manually update a firmware?
3. is there a firmware available to download for possible manual firmware update?

Not sure... Common advice here is to never upgrade
But if you want to play with fw, everything you need is there: https://forum.samygo.tv/viewtopic.php?f=70&t=9497

not sure why but after some more resets and re-setups the apps are downloaded again and available in smart hub... and without usb stick... - very strange...

final note: thank you for this support and I think I have a clean tv now

... and rooted again with usb stick method. all is working now