Hello
Thank you for your question and reaching out.
I can understand you are facing issue with GPO in RDS environment,
You can Loopback Policy processing. Move the RDS server to a new OU. Link your GPO to this OU. Configure Loopback Policy processing in this GPO to Replace or Merge mode (depending on whether you want to replace the users normal GPO settings with these GPO settings or merge the users normal GPO settings with these settings). I suspect you'll want Merge mode.
Now when a user logs on to the RDS server the User Configuration settings from the GPO linked to this OU will apply in addition to or in replacement of the users normal GPO settings. This way the drive restriction is only effective when logging on to the RDS server and not on their workstations.
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