Unreal engine cannot find a session on another computer

Howdy. So I have a multiplayer game that uses the advanced sessions plugin. However, for some reason, when two players try to play from different machines, the session the host creates cannot be found (Even if they’re on different/same network). The session can only be found if the host starts up another instance of the game on their same machine. What could be some causes for this?

Note: I specifically know sessions cannot be found because I check what the length is of FindSessionsAdvanced.
If necessary, here is the tutorial I followed to create the session browser.
https://www.youtube.com/watch?v=NW4QHiK6YbQ