Hi @Burkhard_Mielke,
Thanks for letting us know you’re still having issues, and apologies for the trouble. Since your post is unrelated to the brief interruption we experienced earlier, I’ve moved your posts into their own thread.
So we can better assist you, please provide a brief description of your current setup using this link as a guide.
Make sure to describe your network configuration/topology, including any networking hardware currently in use, so we can have a clear understanding of how your devices are communicating.
Since experiencing this issue have you tried rebooting your Core machine?