Nodes, interfaces, or volumes that are assigned to an additional polling engine (APE) cannot be...

For objects assigned to an Additional Polling Engine, the main SolarWinds Platform server and Web Console must be able to resolve and communicate with the APE. SolarWinds scalability-engine guidance states that port 17777/TCP is used by the SolarWinds Information Service for bidirectional communication between the Additional Polling Engine and the main polling engine. If port 17777 is blocked on the APE, object editing and platform module communication can fail for objects owned by that APE. An invalid DNS entry for the APE can create the same practical problem because the main server cannot reliably reach the APE by name. Port 5671 is RabbitMQ messaging and is important, but option C is the more direct fit for editing/access through Information Service.