I think i figured this one out.
Never needed to before, but i thought maybe it's as simple as Kodi starting before network is fully started.
Set wait for network for 3 seconds and the issue is gone.
That makes perfect sense - it just rang a bell with this:
PVR addon doesn't load if TV backend server is unreachable
Although it's odd disabling / re-enabling worked for dvbviewer but not for dvblink.