Yesterday I updated the IP addresses for the servers and it shows the new IP on the Polling Engine page. I just ran the configuration wizard on all the servers that moved and received no errors. I also cleared asp.net cache on the main poller. It still seems to be happening.
I just used the SNMP walk tool on the server to see if it has any problems. It did not, it was able to pull the SNMPwalk without issue. It seems to be a poller issue.
Is there a log where these "add node" failures get written to?
Did you end up finding anything out here? I'm experiencing the same error on a new APE in a new network.
The issue was that the main poller couldn't communicate on 17777 to the APEs. We opened the ports and it started working.
Sounds to me like you are having a communication issue between the APE and the primary server. I would start with a tool like psping to make sure the ports are in fact open. You can run it from the APE and connect to the primary server.
If you moved an existing server is it possible you now have different group policies applied?
Check that .NET is the same version across all servers.
Windows updates are installed evenly across all servers.
Please keep this post updated, I am about to attempt this same task.
Had this issue also. In the web log I found:
Message: Exception of type 'SolarWinds.ApiProxyFactory.TransientApiProxyException' was thrown.
Message: There was no endpoint listening at net.tcp://xxxserver01.domain.internal:17777/orion/core/businesslayer that could accept the message.
On the Additional Polling engines bussiness layer log i found:
2019-01-21 10:40:23,375  ERROR SolarWinds.BusinessLayerHost.PluginInstanceAppDomain - Plugin "Core Business Layer" failed to start.
System.ServiceModel.FaultException`1[SolarWinds.InformationService.Contract2.InfoServiceFaultContract]: RunQuery failed, check fault information.
Source entity [Orion.Package] not found in catalog (Fault Detail is equal to InfoServiceFaultContract [ SolarWinds.Data.Query.EntityNotFoundException: Source entity [Orion.Package] not found in catalog
Comparer the catalog "C:\Program Files (x86)\SolarWinds\Orion\Information Service\3.0\Schemas" on APE and core server and found 2 extra files on APE, files for "NetflowFastBitSchema". Deleted the files and restarted Module engine service and all worked again.