Hello,
The most likely reason is:
One of your PC (I think mlwphpenvy360 ) is not able to authenticate a MS mail user. That's why you cannot login with your credentials directly.
So, I suggest you abandon pre-auth, in a straightforward way, you need to disable NLA in all your 2 PC:
Open gpedit.msc applet.
Navigate to Computer Configuration -> Administrative Templates -> Windows Components -> Remote Desktop Services -> Remote Desktop Session Host -> Security.
Enable Require use of specific security layer for remote (RDP) connections and select RDP as Security Layer.
Disable Require user authentication for remote connections by using Network Level Authentication policy.
Reboot Terminal server.
If you don't have group policy options, try to disable NLA from UI. Then log in to your account as if you were logging in locally.
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