Remote Desktop Connection Manager Unknown Disconnection Reason 3079 Jun 2026

Microsoft no longer officially supports the original RDCMan (last updated in 2014), but a newer is available on GitHub. The old version often triggers 3079 with modern Windows 10/11 or Windows Server 2019/2022.

With the rollout of CVE-2018-0886 (CredSSP encryption oracle remediation), Microsoft introduced layer-by-layer encryption requirements. If your RDCMan client is running a newer OS (e.g., Windows 10/11 updated) but the target server is older (Windows Server 2012 R2 or older without patches), the encryption level negotiation can fail. RDCMan often presents this as 3079 rather than the more specific "Encryption mismatch" error. Microsoft no longer officially supports the original RDCMan

Alternatively, try connecting via the standard once. If it works there but fails in RDCMan, the issue is likely how RDCMan is handling the handshake. Step 5: Check for Session Limits If your RDCMan client is running a newer OS (e

qwinsta /server:localhost

RDCMan is extremely sensitive to early-stage connection failures. If a network device (firewall, router, switch) resets the TCP connection before the RDP negotiation completes, the RDP control has no context to assign a proper error code. Result: 3079. If it works there but fails in RDCMan,

You might notice that the standard connects fine, but RDCMan fails with error 3079. This happens because RDCMan handles credentials and security negotiation slightly differently. The CredSSP fixes above apply to both, but RDCMan may need the .rdg edit (Fix 4) even after the server is updated.

Ensure the user isn't trying to connect outside of their permitted window.