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UDP port 68 could not be opened.



Hello, I'm running into a issue on a probe server with the following probe device error:

The UDP port 68 could not be opened. To resolve this issue, make sure that the port is not in use. Also make sure that the port is opened in your firewall or create respective NAT rules for this port. (code: PE091)

I checked the firewall, port 68 is open and not being used by any other app. All IPs are internal and no NATing is needed. I have two PRTG server in failover config, and two other probe servers besides the one with the error and they all are reporting no errors. Any suggestions where to start looking?

port prtg udp

Created on Nov 10, 2021 6:02:18 PM

2 Replies




Which sensor type are you using exactly? If you want us to take a closer look, feel free to send us screenshots of the error message as well as screenshots of the sensor settings to [email protected]

Created on Nov 15, 2021 8:38:08 AM by  Timo Dambach [Paessler Support]



It was under Probe Device / Probe health but this morning it is showing green/ok. Not sure what would have been blocking port 68 but apparently it's resolved. May have been something the networking team was doing with the switch feeding that server.

Created on Nov 15, 2021 2:17:50 PM

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.