Cant get system management (processes) on remote office PC's

Cant get system management (processes) on remote office PC's

I can click "manage" on PC's in the LAN (relative to the DC-server) and the local PCs will show processes, but when I connect to a remote PC it says unavailable every time.

" Your System Manager session has been disconnected because the agent is not reachable" 

 1/ Am I missing a setting for managing this remote PC?
 2/ Where can I see the Ping distance (as measured in ms) for diagnostic purposes



I can remote-access the remote PC using the HTML5 viewer...
WAN ports forwarded to DC server:
8443 tcp
8444 tcp
8031 tcp
8032 tcp
8081 tcp
8082 tcp
8020 tcp
8027 tcp
8383 tcp

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