Enter and exit airplane mode in order to restore my data connection (COS 12.1)

Im was on YNG2TAS2I3 and for some reason, my data connection usually does not work. The signal is stong but it shows a "!"; I can make phone calls but can't use anything internet related. The quickest fix for now is enter airplane mode and then exit. It usually restores the connection after that.

I upgraded to YOG4PAS1N0 and same thing.

This actually never happened to me on this pone before. What could be wrong?