When joining a friend my screen is stuck on "Locating Server"

When trying to join my friend on a world in which we have played various times, the screen stays on "Locating Server", I've tried turning my computer on and off. Restarting Minecraft, and more. It's starting to get very frustrating since we have been trying to play for 2 hours now. Every other world works, whether it be mine or theirs, including servers.