When working with R80.X (both R80.10 and R80.20.m1) management servers, one of the issues is that you cannot connect to SMS with your SmartConsole, although the machine seems to be started and running fine.
There are several scenarios where it might be important: upgrade in place from a previous version, migrate import operation or even a reboot of your running machine.
With migrates and upgrades, it takes a significant effort after the fact to update MGMT DB, and it is usually hart to guess if the process is finally complete.
When you perform a maintenance operation or even reboot your production server, loading DB and bringing CPM process to a ready position may also take time.
However, there is a small trick that can save you some time and efforts in figuring out whether your management is finally in ready to receive a SmartConsole connection.
From a console or SSH run $CPMDIR/scripts/check_cpm_status.sh script.
When it shows CPM server started, you are good to go.
UPDATE: As Tomer Sole mentions in comments, you can alternatively use
$MDS_FWDIR/scripts/cpm_status.sh which works properly in both MDSM and SMS environments.