App occasionally goes to the wrong port

[kourylape]

We have 4 main services we're forwarding:

• Ruby on Rails Backend on 9000
• React SPA on 8080
• CloudBeaver DB Client on 8978
• GraphQL on 5000

The rails app runs on port 9000, and I've seen situations where loading a page will render a 404 from another app.

For example, http://blub-9000.use.devtunnels.ms/login should be a SSR login. Occasionally, when loading that page it will show the 404 page from CloudBeaver (8978) and the SPA (8080). The URL always remains http://blub-9000.use.devtunnels.ms/login in the browser so it's not a redirect or anything. It will randomly happen on any page at anytime, just was using /login as an example.

I've confirmed using https://blub-9000-inspect.use.devtunnels.ms that the request headers remain the same even during the 404s. Just the responses differ.

Edit: When using localhost:9000/login, we've never seen any these 404s.