Other Players Can't Join My Worlds

Whenever my friends try to join my world they can't
**What I expected to happen was...:**
They would be able to join the world

What actually happened was...:
They couldn't join the world

Steps to Reproduce:
1. Launch the game
2. Click on singleplayer
3. Join a world
4. Invite a friend or they can join on their own
5. Then they can't join