For all bug reports, please provide detailed information about the problem. “is buggy” or “loosing connectivity” is probably not very helpful for the analysis.
I have submitted the related description in the bug tracker.
Meanwhile I could mitigate a behavior of point 3 by explicitly define the ip of the callback server in the homematic.cfg. It seems that the auto discovery feature is not working. I have create the report in the bug tracker.
Also the “not all rules load during startup” bug known from OH 1.8x for so long, has hit me again. For this bug I have also created a report in the bug tracker.