"Unable to connect to the world" message is constantly showing up whenever someone tries to join my world

Can you confirm these:

1. You and the other player are on the same version of MC

2. You and your friend have a good internet connection

3. If on WiFi, your router is not blocking inbound connections

4. If on WiFi, no other applications are using the same port MC is using (usually is port 19132)

5. The world's multiplayer settings are on

Thank you for your report!
We're tracking this issue in MCPE-36190, so this ticket is being resolved and linked as a duplicate.

If you would like to add a vote and any extra information to the main ticket it would be appreciated.

If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.

Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki

I tried using your steps and it still doesn't let my friend join