This isn't necessarily Tunein's fault. They take the exact feed provided by the broadcaster and pipe it to you no questions asked - they don't downgrade the stream if it's too bandwidth intensive. Most stations will use a mobile-friendly bitrate (mine is 96k/sec) but some that are very music heavy will send out an extremely high bitrate for maximum fidelity. Unfortunately, even if you have full bars on 3G, your downstream might not be good enough to receive these very high bitrate streams, which is why the message specifically says connect to Wifi to play. 3G is not fast, which is why more and more carriers are moving to LTE. There's a good chance your LTE phone would have handled this particular station just fine, but even that can't be guaranteed compared to a Wifi connection to a Cable/DSL modem.