Thank you for the post! There are multiple reasons why a Probe disconnects. If you have confirmed that no firewall, ACL or security software block the traffic, a time sync could be also the source.
In the case that the Core Server and the Probe have not the same time, PRTG tries to adjust this. If this fails, a possible result is that the TCP connection is dropped.
Other reasons could be:
- Wrong Access Keys
- IP is listed in the "Deny IPs" list (Setup > System Administration > Core & Probes)
- Wrong PRTG Version installed
- NPCAP Loopback Adapter (this network adapter is sometimes installed and used by the Probe for the Core connection. Since it's a loopback adapter, this will never success)
However, to take a closer look at your issue, I would recommend to open a case. Therefore, please write an email to [email protected]. Please mention this KB article (via an link) or the case number "PAE1292966" in your email.