End client connection when reverse web proxy fails

Question

I am trying to get nginx to close its connection to the client when the connection to the reverse proxy server is lost.

I used to have a noVNC client directly related to websockify . For each connection, websockify creates a child process to handle it. If this child process crashes (for example, being killed), noVNC will detect a lost connection, allowing it to be handled accordingly. For example, an error message display and a reconnect button.

If I changed this setting to use nginx as a reverse proxy, the noVNC client will not be able to determine that the connection to nginx in websockify has been terminated. The result of this is that the noVNC client is frozen.

How to make nginx detect that websockify has completed and close the connection it has with noVNC?

If it has any bearing, the previous method used an unencrypted connection between noVNC and websockify. With nginx there is an encrypted connection between noVNC and nginx and an unencrypted connection between nginx and websockify.