Enterprise unattended robot disconnected from community orchestrator intermittently while job running

I requested enterprise trial on community cloud orchestrator, and installed enterprise studio and robot from msi file. But these days while running job from orchestrator, the robot disconnected frequently and back to connected while job executed ended on robot. excluded the network connection issue, is there any other possible situation caused this and solution to resolve it?

anyone can help on this?

robot OS version: win10 v1904
robot version: 21.4.4
orchestrator: community cloud