SolusVM 2 CR status in UI is Unavailable while VPS'es are running properly

Symptoms 

VMs are running properly and CR is functioning, but the status is Unavailable in UI.

Cause

Environment misconfiguration

Resolution

1. Ensure SolusVM 2 updated to the latest version and it's the same between Management server and Compute Resource.

2. Restart solus-agent.service on the CR.

   # systemctl restart solus-agent.service

3. Ensure the required ports are opened and reachable between Management server and Compute Resource:
   What ports are required to be opened for SolusVM 2?
4. For additional analysis check the log entries: 

   1. Management server:

      # journalctl -xefu docker

   2. CR:

      # journalctl -xefu solus-agent.service