If Big Walk crossplay is not working, confirm that everyone is on a supported version, then have the host start the saved session and share the newly generated Join Code. Official crossplay covers Steam on Windows and Mac, PlayStation 5, and Nintendo Switch 2.
Use the correct join method
Friends on the same platform friend list should see the host's game in the friends-game menu. Players on different systems, or players who are not platform friends, should use the short Join Code shown when the host starts the session.
A Join Code is generated every time the host starts a session. Do not reuse a code copied from an earlier session, because the official FAQ defines it as a new unique code for the current host start.
Confirm the host and save state
The host is the keeper of the save and must start first. Other players can connect only after that session exists, and everyone disconnects when the host ends it.
If the group is continuing an earlier journey, make sure the original host selected that saved world rather than another player creating a new one. This does not fix every network problem, but it verifies the official session order before troubleshooting outside the game.
Keep the platform claim accurate
Crossplay support does not extend the official platform list. PS4 and the original Nintendo Switch are not listed, so a player cannot join from an edition that does not exist on those systems.
If a current Join Code still fails after every player updates and the host restarts the session, use the contact path on Panic's Big Walk support page. No official source currently publishes game-specific firewall ports or a manual save-transfer workaround, so those should not be presented as confirmed fixes.