It seems link cable functionality is currently not working.
Firefox error
Uncaught (in promise) FirebaseError: Missing or insufficient permissions.
Could not open boot ROM: No such file or directory.
Chrome error
Could not open boot ROM: No such file or directory.
Aborted(Stack overflow! Stack cookie has been overwritten at 0x001b1550, expected hex dwords 0x89BACDFE and 0x2135467, but received 0x00000000 0x00000000)
Uncaught (in promise) TypeError: Cannot read properties of null (reading 'AL')
When the link cable connection is started (attempted with Tetris GB, Pokemon GBC, and Super Mario Bros Deluxe GBC), the host's screen goes back to the game but with an infinite spinner, and those errors.
Also just to add some more context to rule out any outliers:
  • I've confirmed the same errors when using the share link with myself (same account, so same ROMs. I specifically tried GBC Pokemon Yellow + Pokemon Red)
  • I've confirmed the same errors when using the exact same ROM and using the link cable URL from someone else between 2 different AfterPlay accounts