In order to provide the greatest stability, the following steps should be performed:
1- upgrade all hubs in the environment to at least 7.93.
2- upgrade the robot (controller) on all the hubs to at least 7.93.
(note: as a best practice, it would be advisable to upgrade all robots in the entire environment to 7.93, not just the hub robots.)
3- add the following configuration key/value to the <controller> section of the robot.cfg:
reuse_async_session = 1
4- add the following configuration keys/values to the hub.cfg:
in the <hub> section:
check_spooler_sessions = 1
in the <tunnel> section:
protocol_mode = 3
max_heartbeat = 30