Hey @Timo_Fleckenstein — Thank you for sharing you report with us!
I moved your post to this main thread regarding this topic so that way we can keep similar troubleshooting all in one place to make it easier for others to find later.
To start, may I ask that 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.
May I also ask that you confirm the following:
- You mentioned you tried rebooting above. Did you do this with the Core, remote devices, and networking hardware?
- Is there any active firewall or antivirus on the Core machine? If so, have you tried disabling?
Thanks,
Dylan