Tried to figure out what the problem is:
- USB connections?
- Tried a different USB hub
- Tried to connect cables directly to the computre
- Tried different USB cables
- Power supply?
- Tried to connect devices directly with original connectors
- Bought a new power supply - well this was a good idea anyway. Now I don't have any 12V cigarette lighter plugs left. And the new power supply has up to 30A !!!
Nothing made a difference. Then I tried the devices themselves. I exchanged the FLI Atlas focuser for the Robofocus focuser - no difference (only that I experienced focuser slip again).
After observing it more closely, I realized that the guider always seemed to be involved (when it captures an image it throws an exception but only if another device is active at the same time!). Tried an unguided session - but that didn't work either.
At last I thought about the computer itself! I plugged all USB cables into the new USB hub that I bought and connected that back out to my laptop. NO ISSUES!!!
I tried this now several times, every time I use the NUC I get these issues. Every time I use the laptop, everything works!!!
Hmmmmmm, can I exchange the NUC? Get it repaired? A friend of mine pointed me to the DS87 - sligthly bigger but this one would have the advantage that it as a serial connector! (that would get rid of the serial-USB adapter).