We have a RDS (Remote Desktop Services) deployment, and recently went through the process of installing the HTML5 web client as per the directions at:


Our deployment is hosted on domain A, which has an active directory instance. There is also domain B with its own active directory instance, there is a two way trust between the two.

The problem we are having is that the traditional RD Web Access works fine for all users, but when users from domain B log on to the HTML 5 web client and try to open an app they get a message "We couldn't connect to the gateway because of an error". At the same time the browser console shows the following error:

Connection(ERR): The connection generated an internal exception with disconnect code=GatewayProtocolError(52), extended code=, reason=Gateway tunnel authorization failed with error code=2147965403

During troubleshooting we’ve tried:

  • Verified that required ports are opened.
  • Disabling all firewalls between gateways, brokers, and session hosts – same error.
  • Re-applied the publicly trusted cert to the HTML5 client (via Import-RDWebClientBrokerCert) – same error
  • Verified that the proper cert was bound to the HTML5 client – same error.
  • Enabled NTLM by setting the GPO: Computer Configuration -> Policies -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> Network Security: Restrict NTLM: NTLM Authentication in this domain. To “Disable” (within same domain as RDP) – same error.
  • Ran regsvr32 wksprtps.dll (dll was already registered, but tried it anyway)
  • Verified that the required KB4025334 from July of last year was installed or not necessary (OS was up to date)

Any ideas on other areas we can look at?

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