Once you know the app is not simply in Offline Mode, work outward from the connection. Spotify's official page recommends checking other apps and websites first, then using the appropriate Wi-Fi or mobile-data fixes for the connection you are on. That is practical advice because it stops you from reinstalling Spotify when the real problem is a router, a dead mobile connection, or a device-level network issue.
If you are on home Wi-Fi, restarting Wi-Fi on the device and restarting the router are both in scope before you do anything more drastic. If you are on mobile data, the equivalent logic applies: confirm the connection is actually live and not just showing signal bars without working data.
If the issue seems to be limited to one device, move to device-level isolation. Spotify's other troubleshooting guidance for playback problems suggests testing another device or the web player, making sure the device OS is current, checking available storage, and clearing or reinstalling the app if needed. That matters because an offline message can sometimes be the symptom of a local app problem rather than a pure network failure.
The quickest way to avoid wasted effort is to keep the order disciplined: check Offline Mode, check whether the internet works elsewhere on the device, try another device or the web player, and only then escalate into reinstalling or deeper troubleshooting. That sequence mirrors Spotify's own support logic and usually gets you to the real cause faster.
Source: Official: Spotify is offline