Hi @Ionutb1984 and welcome to the Sonos Community!
Apologies for the delay in responding to your post, and sorry to hear about this issue you are experiencing. Can you confirm what music source your playlists are pulling from? For instance Spotify, Apple Music, your own locally stored music etc.
It may be worth rebooting your speakers and wifi router if this has not been done recently, as it can help with these kinds of issues. If powering off and back on your devices does not help, please Submit a Diagnostic from the Sonos app the next time the issue occurs and we can take a look for you.