If you're using mobile data, it could be Cricket. If you're using WiFi, it's not, so check your WiFi connection.
But if it's not your WiFi connection, it's a failure in the phone and since it's still under warranty, either Cricket (if you bought it from them) or LG should repair it with no charge. (Don't let anyone tell you that they don't repair phones - the warranty is legally enforceable. If Cricket doesn't do repairs, they can replace the phone or they can send it to LG, that's their choice, unless your contract with them says that you have to send it to LG.)