SignalR can't connect when deployed behind AWS EB - amazon-web-services

Question

I am trying to use SignalR on an application hosted in AWS EB, with an application loadbalancer in front.
It works perfectly fine when I test it locally, but when deployed, the websocket can not establish a connection and returns:
"Error: Failed to start the connection: Error: There was an error with the transport."
And
"There was an error with the transport. at WebSocket.o.onerror [as __zone_symbol__ON_PROPERTYerror]"
I have tried adding a middleware at the very start of my pipeline, that logs if i get a request for my hub, and this works, so I dont think it is the load balancer or anything AWS Related.
If i call the URL with Postman websocket, I get a status code 400.
I have followed the MS guide and added the configuration for JWT auth
jwtTokenOptions.Events = new JwtBearerEvents
{
OnMessageReceived = context =>
{
var accessToken = context.Request.Query["access_token"];
// If the request is for our hub...
var path = context.HttpContext.Request.Path;
if (!string.IsNullOrEmpty(accessToken) &&
(path.StartsWithSegments("/signalr")))
{
// Read the token out of the query string
context.Token = accessToken;
}
return Task.CompletedTask;
}
};
And as I said, it works fine locally. Any suggestions are most welcome

Answer 1

I fixed this by enabling web sockets for the IIS on the eb instance.
I did this by creating an eb extension with the following command
commands:
01_install_websockets_feature:
command: "%SystemRoot%\\System32\\dism.exe /online /enable-feature /featurename:IIS-WebSockets"
ignoreErrors: true