After updating from PRTG 8.x I have some SNMP sensors that do not work anymore.

All of these sensors seem to have in common that they are located in in the same network segment(s) and my PRTG system / probe system is a multihomed system (i.e. has more than one network card).


Article Comments

Important note: The information in this article is outdated. We do not officially support any updates from PRTG 7 or PRTG 8! It is also technically not possible to directly update from these versions to current PRTG versions. We recommend that you perform a clean installation of the latest PRTG version.

Please see PRTG Manual: Update From Previous Versions


With version 9 we have changed the behaviour of SNMP request. SNMP requests are now using the Outgoing IP address setting from the PRTG Probe Administrator application. PRTG 8 did not use the setting, it always used the "auto" setting.

When updating from V8 to the current PRTG version, a previously incorrect setting now becomes apparent.

In order to fix this you must open the PRTG Probe Administrator, select the Outgoing IP Settings tab and select the "auto" setting (or another setting, depending on your network setup).


Sep, 2011 - Permalink