Why do I suddenly have problems with iTunes?

Hi. It started 2 or so days ago. When I try to listen to a song that is not downloaded to my iPhone it plays with huge pauses almost every second. When I try to download it to my iPhone it takes about 8 minutes to download one song. I use wi-fi. The connection is fast. The internet works well. What can be the problem?

So that you can slowly and painfully resolve it