Have a Galaxy J1 2016 which will work perfectly happily on the Vodafone network on 3G/4G for several days, then suddenly stop having Internet access until the APN settings for the Internet are requested and installed again. Voice and txts functions as normal.

It has also "fixed itself" once after leaving it for a while, but usually trying to do things like send messages on the Facebook messenger app etc will refuse to work unless on wifi once the issue has begun, until it is "reset" as per above.

Any thoughts?