Slow mobile data on Galaxy S4

[AC Question]

Have S4 and using BT mobile for data. It works but really slow - wifi is fine Any ideas it's driving me mad I tried a different sim and no better.

 

[srkmagnus]

Welcome to Android Central!

What do you mean by "BT" data? Are you referring to Bluetooth? You should only connect to WiFi or Mobile Data (carrier) unless tethering via Bluetooth - please clarify.