Halo 5 Guardians Local Server Help

So I used to be able to set up a local server on my older computer (The windows 10 app), but for whatever reason I cannot get it to work with my new rig. It is connected to the same network as the Xbox, they both are set up with an ethernet. What am I missing? Both my machines are up to date too. Id imagine this was a case of the App not being updated in so long. But I am not sure. Anyone else try using the App?