Hello,
Thank you for posting in the Microsoft Community forum.
May I know what version of the remote desktop client you are using? Note that the Microsoft Store version of the client does not support multiple monitors.
You can refer to this document to try to configure multiple monitors:
Configure multiple monitors for your dev box - Microsoft Dev Box | Microsoft Learn
I hope this helps. If the problem persists, please continue to contact us.
Best regards
Jacen
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