Use this signal map to find where a MIDI connection stops.
Sends notes→Data cable / interface
Carries MIDI→Browser
Supports and permits MIDI→Classroom
Shows local input→Peer
Receives shared input
Test each link
Keyboard: play one comfortable note.
Cable or interface: check the correct port and a data-capable connection.
Browser: allow requested MIDI access in a supported browser.
Classroom: confirm your own note appears before testing the remote display.
Peer: take turns and identify each participant’s input.
Three diagnostic cards
Sound but no coloured key: audio can work while MIDI does not. Check the data path.
Local colour but no peer colour: first confirm that the other participant’s own input works.
Different intensity: compare note attacks; the display represents MIDI velocity, not microphone loudness.
Useful information for support
Instrument model, cable or interface, browser, and the first point where the signal fails.
Check the browser requirements in MDN and the instrument manufacturer’s instructions for device-specific setup.