Netcode works perfectly on one network, doesn't work on another.

This code isn’t necessarily a code oriented question, but I was hoping someone might have an idea of what to do. I’ve got networking working in this app I’m working on, where I have an android client connect to a desktop server running on a laptop. I have two routers in my house, where one is just an old linksys and the other is an apple airport extreme. My app works great when both server and client are connected to the linksys. However, the client cant seem to find the server when connected to the airport. I’m using libgdx’s built in networking if that helps. Does anyone know what is the issue here?