My confluence is running behind a reverse proxy server, my users connect to the linchpin/confluence itself via webbrowser and there is no VPN necessary. Using the Linchpin Mobile app does not work. The user are not able to connect during the setup process.
The problem is most likely caused by the HTTP-headers that are changed by the proxy server. Linchpin mobile needs the host header to work properly. Often the proxy server changes the host header to be some internal address.
Linchpin mobile supports the x-forwarded-host header. It can be used to deal with the described problem. Then proxy server should set the header to the real host name.
Your proxy server changes the headers to the following:
Set the header to get linchpin mobile working