There could be multiple scenarios where a user or multiple users can see the 50331655 RDP error code.
Scenario-1:
External users were getting RDP error code 50331655 when attempting to connect to Workspot Desktops. Although the SSL certificate was correctly set up on the Gateway servers, the old certificate still appeared when the URL was accessed externally.
Root Cause
The Gateway infrastructure is front-ended by a load balancer that handles SSL termination for external connections. While the certificate was updated on the gateway servers, the load balancer continued to use the outdated certificate, causing external users to receive the wrong SSL certificate.
Troubleshooting Performed
Verified that the updated certificate was reflected in Gateway Manager and IIS. Removed and re-imported the certificate under IIS > Personal Certificates, followed by a server restart. Despite these actions, the issue persisted. Further investigation revealed that the load balancer was still serving the old certificate.
Resolution
Updated the new SSL certificate on the load balancer. Restarted necessary services and verified that the correct certificate was reflected externally. Confirmed successful external access to Persistent Desktops.
Key Takeaway
When updating SSL certificates for Gateway environments, ensure the same certificate is also updated on the load balancer or network appliance, especially if it handles SSL termination for external connections. Overlooking this step can result in certificate mismatches and access errors for external users.