RDP Issue – Error Code 0x3000008 When Connecting to External Domain

Hi all, We're encountering an issue when attempting to establish an external Remote Desktop (RDP) session to a domain-joined system.

When users try to connect via Remote Desktop, the following error is returned:

Remote Desktop Connection There was a problem connecting to the remote resource. Ask your network administrator for help. Error code: 0x3000008

We've verified basic connectivity and DNS resolution, but the error persists. Has anyone seen this specific error code before? Any insight into what policies, firewall rules, or RDP settings might cause this?

Appreciate any suggestions, troubleshooting tips, or guidance.

Thanks in advance!