I don’t really know how I ended up posting this in a completely wrong sub forum… I was so dumbfounded by my problem and have been searching until deep in the night to find a solution so I guess I got a bit overpowered by the forum structure. Of course if I would have gone to the right sub I wouldn’t have had to post in the first place… After a good night sleep it seems clear to me now. Hopefully 2020 is done with me now.
I had a double problem. This ( https://forum.navigraph.com/t/simlink-waiting-for-authentication/2045 ) one stopped simlink from connecting so the simlink status dialog was not available and Firefox starting up the wrong program, did the rest. All is solved now.
My apologies and thanks for the quick reply!