Also, it might help to quit out of all other applications before you want to stream with Spotify as music streaming might be memory intensive on an older device like yours. I think you can end tasks on your phone by double clicking the home button and swiping right on all the apps you want to quit out of.
It's not an internet issue. My brother that lives with me has an iPhone 4S and an iPad 4, he also has Spotify Premium. He has no problem streaming songs from his devices. And I know the issue isn't my device either. I used to do it all the time.
Hi @Drumrocker365 is your brother also on the latest verison of the Spotify app? Could you confirm the iOS of those devices too?
Have you given the web player a try? Is that working for you when you try to stream?
It looks like you may be having a different issue. The app doesn't crash on launch when connected to wifi. I can play songs fine that are available offline (since I am a Premium subscriber), but songs that I want to stream and not nessisarily download, don't work. It causes teh app to crash.