Can multiple projects in a Visual Studio solution work with dev tunnels?

Hello @John Mann,

Welcome to Microsoft Q&A forum.

Please kindly check the explanation here: Specify the active tunnel

A project or solution can have multiple tunnels, but only one at a time is active. The Dev Tunnels flyout in the debug dropdown can specify the active tunnel. When there is an active tunnel, it’s used for all ASP.NET Core projects that are started in Visual Studio. Once a tunnel is selected as active, it remains active until Visual Studio is closed.

So, only one tunnel at a time is active, and it should be used for all started projects. Maybe try to launch VS and run your projects again? Also, not very sure how you selected/configured the tunnel, perhaps you need to follow the related documents and check/configure again.

Sincerely,

Tianyu

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After upgrading to a later version of Visual Studio (I'm now on 17.11.0) I no longer see this problem, so it all appears to be working ok now - thanks for your patience.