I'd posted a support ticket as well, am going to paste their feedback here so it might help others ? Obviously, details are current at time of posting the info.
Net-SNMP is compatible with SolarWinds Orion. You need to install and configure net- SNMP on the Linux systems to get performance information and you will likely have to configure IPTables on the Linux system to allow Orion to talk to it.
Also, please confirm if the Net-SNMP is at least 188.8.131.52. Use "snmpd -v" to check version of net-snmp installed. If it isn't, you might want to contact the vendor, and request them to update the SNMP-agent.
Port 161 will need to be open as one of the default application ports for SNMP traffic.
You may also try to run an SNMPWalk to the Red Hat enterprise to test if the NET-SNMP responds.
Best way to test this is to run a packet capture on the NPM. Filter it by IP address of the Red hat server and then test the credential. In this way, you will see exactly what’s going on with the device.
At present, I've got one of my tech team working through the above... watch this space...
Well, if anyone refers to this in future, it appears that the Linux builds we are using have integrated Firewalls (which are enabled) it seems that this (along with some SNMP.conf settings) was the main part of the issue.
Once these were amended, communication could take place.
We also did the following:
Updated Net SNMP to a more current release (that is supported on the Linux builds)
Amended the SNMP.conf files
Still working out the various minutiae of monitoring, but we're getting there
Big thanks to Erickson from Solarwinds support for his assistance in getting this sorted!