Check the Client-to-Gateway and Gateway-to-APPX Connections

Connection	Setting	Tested endpoint
Client to gateway	DSN Host and Service; client's services file	localhost:1992
Gateway to APPX	Dictionary appx.env APPX_DATA_SERVER	localhost:31062

Test each endpoint separately. An open gateway port does not prove APPX authentication or file access. Configure access through the site's normal firewall process. The client services-file mapping resolves a TCP name; it does not start a Windows service.