Windows app cant connect to Remote Desktop Gateway

Question

When i try to use the iOS "Windows" app to connect to a computer from outside the network through a Remote Desktop Gateway the app errors out with error code 0x3000066

Its not a network or rd-gateway configuration issue as it works just fine using mstsc on Windows or RD Client on Android

Answer 1

Hello Alec,

This issue is not related to Windows for Business or Windows 365 Enterprise. It is specifically tied to the Microsoft Remote Desktop iOS client and how it handles connections through a Remote Desktop Gateway.

The error code 0x3000066 has been reported by multiple users after recent updates to the iOS Remote Desktop app. The problem is not with your RD Gateway configuration, since mstsc on Windows and the Android RD Client connect successfully. Instead, it is a client-side defect in the iOS app’s handling of RD Gateway negotiation and authentication. Microsoft has acknowledged that certain versions of the iOS and macOS RD clients fail with this error when connecting through RD Gateway, particularly against Windows Server 2022 or newer TLS configurations.

The first step is to confirm you are running the latest version of the iOS RD Client from the App Store, as Microsoft has released incremental fixes. If you are already on the latest build and the error persists, the only supported options are either to adjust the RD Gateway’s SSL/TLS certificate chain to ensure full trust on iOS, or to wait for Microsoft to release a patched client. At present, there is no server-side configuration change that guarantees resolution, since the same gateway works fine with other clients.

In short, this is a known limitation of the iOS RD Client, not a misconfiguration on your side. If updating the app does not resolve it, the only compliant path is to monitor Microsoft’s release notes and apply the next update when available.

I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!

Domic Vo.