I forked this into a separate thread.
Think we need some more context. Are you saying using localhost:port of your MacOS device does not work with the app proxy anymore? In the recent releases, an app proxy related change that happened is that we set the Host header to the initial request endpoint. Would your set up be affected by this change by any chance? Related issue in NPM - https://github.com/NginxProxyManager/nginx-proxy-manager/issues/127