If monitoring a Linux host using Infrastructure Agent hosted ona Windows Agent Manager(FGLAM), it will use SSH connection to port 22 on the target Linux host and will communicate back to Agent Manager using random ports.
Using Nestat from the Linux Monitored host, we can see how it's returning back on the random ports to the Agent Manager:
netstat -ant | grep "IPofFGLAM"
Note: The Agent Manager in Debug mode will provide more information regarding errors/failures.