VS Code on Chromebook Penguin with Remote SSH: Could not establish conntection to the "servername", the VS Code Server failled to start

I installed VS code on Penguin on an Acer Chromebook R11.

I followed the steps for Debian here : https://code.visualstudio.com/docs/setup/linux

It works like a charm but I need to connect to my remote dev server using the official extension RemoteSSH by Microsoft.

Then I configured a .ssh folder for the user with correct permissions : https://gist.github.com/grenade/6318301

Now I get :

Could not establish conntection to the "servername", the VS Code Server failled to start

The detailled log is :

[11:39:39.572] Resolver error: The VS Code Server failed to start
[11:39:39.609] TELEMETRY: {"eventName":"resolver","properties":{"outcome":"failure","reason":"ExitCode","askedPw":"0","askedPassphrase":"1","asked2fa":"0","askedHostKey":"0","gotUnrecognizedPrompt":"0","remoteInConfigFile":"1"},"measures":{"resolveAttempts":1,"exitCode":32,"retries":1}}
[11:39:39.620] ------

I don't have any idea of what it could be. Do you have one ?