WebSocket API gateway connection issue

We are working on the ASP.Net core API application. In this application, we have a SignalR module for notification. We plan to host the application in the AWS environment. We have used AWS lambda service to host the API, we plan to use a Web Socket API to consume the notification/SignalR part.

We are facing an issue with connecting the notification URL. When we tried to connect the Web socket URL from Commandline using Node, it is showing "Unexpected server response 403".

When we tried to consume the URL from the frontend application, it showed the below error. "WebSocket failed to connect. The connection could not be found on the server, either the endpoint may not be a SignalR endpoint, the connection ID is not present on the server, or there is a proxy blocking WebSockets. If you have multiple servers check that sticky sessions are enabled. ."

We are stuck with this issue. Any help to resolve this issue would be appreciable.