You press play and nothing happens. With online radio, the reason is usually one of five things, and only some of them can be fixed from your side.
1. The stream moved or stopped
Stations change streaming providers, rename their streams and sometimes go off the air. A directory listing can point to an address that no longer exists. Skywave DX re-tests stations every night and drops the ones that keep failing; the Report button in the player sends a station to the front of that queue.
2. The stream isn’t secure
Plenty of stations still stream over plain http://. Browsers block insecure audio on secure (https://) pages. Skywave DX passes these streams through a secure connection so they can play.
3. Your browser can’t decode the format
Most stations use MP3 or AAC, which every modern browser plays. A few use formats or playlist types that some browsers don’t handle natively, such as HLS playlists outside Safari. If a station plays on one device but not another, this is the likely reason.
4. The station limits listening by country
Music rights are often licensed country by country, so some broadcasters only stream to listeners in their own country. Nothing on the listening side can change that legitimately; try a similar station instead. Each station page lists similar stations for exactly this case.
5. Your network
Office and school networks sometimes block streaming audio, and a weak mobile connection can stall a high-bitrate stream. Lower-bitrate stations (most station pages show the format and bitrate) cope better with patchy connections.
What about shortwave?
Shortwave through Skywave DX works differently: you listen through a public receiver, which can be busy, offline or simply unable to hear the station at that hour. The app checks for a real signal and tries another receiver if it only hears noise. If a broadcast is silent everywhere, the band may just be closed; see why radio travels farther at night.