You try to connect to an agent and fail with the following error:
"Could not connect to...The connection attempt lasted for a time span...target machine actively refused it"
The Console is trying to connect to an agent, but the agent's service is down.
In addition, the "Deploy agents automatically" (in agent's settings) is disabled, so when you click connect, the Console will try to connect, and if the agent's service is down, it will fail.
In order to fix this issue, the Console needs to start the agent's service while trying to connect.
You can manually select Upgrade Remote Agent from Agent Control, or use the Deploy agents automatically option, to automatically try to restart the agent's service when you connect.
If Deploy agents automatically is checked/enabled, the monitor might have high resource consumption.
There are situations where there are many computers that the monitor cannot connect to (network issue, server is down, etc).
In these situations, the monitor attempts to upgrade them repeatedly, which might use a significant amount of CPU\Memory.