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There could be multiple causes for this issue, however couple of suggestions that could improve this situation.
- Setting profile configuration container.
- Configure RDP Sessions limits.
Want to check if you have set the following profile configuration container?
CleanupInvalidSessions
One more suggestion is to configure RDP Sessions limits (timeouts) through GPOs to set time limit for disconnected sessions and End session when time limits are reached:
Hope that helps.
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