I realize that upgrade is not supported, but thought I would report back before doing a fresh install just in case someone wanted to find out what went wrong with the update.
I can access the HDA dashboard, the list of available apps is empty - this is how i figured the HDA does not have contact with the internet.
Samba is working, I can access the shares that are not pooled. Greyhole shares are unaccessible, typing "greyhole" in a terminal gives me "command not found", i suppose that means it's not even installed.
DNS did not work so DHCP is now turned of in the HDA and I currently run DHCP from my router.
Any hope try to fix this? Or should I burn a Fedora 25 CD right the way?

The latter means some work, carry the box up from the basement, find a monitor, keyboard etc. so if it could be fixed I would be quite happy ...
.frodemann