Hello,
I encounter a similar problem in 4G not observed in wifi, I did not submit the problem because the next day there was a large number of google application updates including Carrier which has already caused this bug often on updates previous updates.
I have 3 phones with 3 different operators, on the other 2 I do not have maj carrier but I have not used it much, the diagnosis will be more on tomorrow.
When that happens, if I'm at home, I activate the Wifi, outside, I put in airplane mode for 1 minute then put it back to normal.
these two operations reactivate the data.