Can't establish WSS connection in iOS and Android builds

We created a test project which can alternatively establish a WebSocket (WS) or a WebSocketSecure (WSS) connection with a test server (echo.websocket.org), using the System.Net.WebSockets.ClientWebSocket class.

We are using Unity 2018.2.8 and everything works fine in the Editor and standalone macOS build, but when we build the project for Android or iOS, the WSS connection doesn't work anymore.

Funny is, we tested the exact same project in Unity 2018.1.4 and the iOS build works fine.

What should we do? Should we submit a bug? (actually we already submitted a similar bug, related to Android only and using WebSocketSharp library, but no one took it in charge as of today).

We are now stuck, so any suggestion is welcome!

 

Side note: same result (WSS not working) in Unity 2018.3 beta and iOS build.

 

A full report and test example was reported here: https://fogbugz.unity3d.com/default.asp?1082184_b1jgq2gplqp9fnja

 

I'm experiencing this on unity 2019.3.6 too. Did you find a fix or is this an editor issue still?

 

We haven't tested this anymore since when the issue was reported. Back then the issue was closed by the Unity team saying it was fixed, but that's all we know.