Help understanding rails port with local tile server

Hello,

I've set up a local tile server that is accessible through mydomain:80. I've also installed the rails port using the installation guide. The rails port is accessible using mydomain:8000. Moreover, I configured the rails port to access the tiles from the local tile server. The map now only displays the part of the world I loaded into the tile server. However, api calls fetching map data is not working and instead only returns boiler plate xml. How is the local tile server supposed to work with the rails port api? Can you not use the local tile server as data source for api calls or have I just missed some configuration?

I'm new to osm and any explanation would be much appreciated!