The number of simultaneous RDP connections is limited by the license.
For multiple users to connect to a VM, you'll need to purchase a Remote Desktop Service (RDS) license and set up a RDS server.
The server would issue client access license to different users or devices (depending on how it was configured) and grant access.
You can also set up Windows Virtual Desktop (WVD) if the machine type you are dealing with is a windows client.
However, you can consider this work around that you can implement and that will serve you for 120 days.
Please, try it out in your test environment and when confident on this work around, you can take it to your production environment.
1) On the server you want multiple concurrent access to, click on Add roles and features
2) Server Roles -> check Remote Desktop Services
3) Role Services -> check Remote desktop services Session Host -> click on Add Feature
4) Install and restart VM
5) Download the RDP file from the portal -> open it in notepad -> administrative session:i:0
6) It will be 1 ... change the value to 0 or delete it
install role > restart > edit the file > login with other users
Please note that this would only last for 120 days, after then, you'll have to get the windows team to assist in configuration.
Also, below are few similar issues for your reference:
Hope that helps.
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