💡 Use a true direct HTTPS audio URL.
The URL must open/stream the audio file itself (for example MP3/M4A/AAC), not a normal web sharing page.
Synology: use a direct/public stream URL if your NAS is configured for HTTPS access. Google Drive: ordinary share links usually are not direct audio URLs and may fail in the browser. Important: the remote server must permit browser playback and HTTPS.