ActionCable - Puma - Nginx - SSL

I'm totally new to ActionCable... Trying to set up Action cable on a Rails 6.0 application (Nginx + Puma). I also have to say my environment is on the cloud (DigitalOcean.com), and that is SSL.

My config/cable.yml :

development:  adapter: redis  url: redis://localhost:6379

My config/environments/development.rb : i've just added this lines

config.action_cable.allowed_request_origins = ["https://my.url.com/"]config.action_cable.url = "ws://localhost:3000/cable"

Of course: my.url.com is my domain.

I'm getting this error :

WebSocket connection to 'wss://my.url.com/cable' failed: WebSocket is closed before the connection is established.

Does anyone have a idea ?

Thanks a lot :-)