Hello,
First of all, you should ensure your client is not a home edition so you can use group policy
1.In your domain, Go to Computer Configuration -> Administrative Templates -> Windows Components -> Remote Desktop Services -> Remote Desktop Session Host -> Device and Resource Redirection.
Find the policy named "Do not allow drive redirection".
Set this policy to "Disabled" to allow drive redirection.
Then you can apply to your server1 and all your clients.
2.Automation in server1(rdp to server2) should be deployed before. looks like:
@echo off
mstsc path\to\server2.rdp
3.Configure default rdp file in your client and server1. (add redirectdrives:i:1 in your rdp file)
Server1: configure rdp file directly
Clients: you can configure in rd web, save your default file in C:\inetpub\wwwroot\RDWeb\rdp
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