I am using MailHog as a Docker container (using docker-compose) and for default configuration everything is OK. Unfortunately when I created Nginx proxy pass I get an error in browser console

VM61:35 WebSocket connection to 'ws://mailhog.sf3.dev:81/api/v2/websocket' failed: Error during WebSocket handshake: Unexpected response code: 400

I guess it is bad configuration problem but as far as I know there is no option to configure MailHog image for docker-compose.