Can't play pokemon go on data - 4G [duplicate]

Usually when people have connection issues like this (when it worked x days ago and now it doesn't work) it's usually just a temporary issue. Here's a few recommendations:

1. Restart the app (a bit obvious). Close the app and reopen it.
2. Check to make sure your phone is connected to the internet via data. If you do not have an unlimited data plan and you have used all of your allocated data for the month or data period, your phone will not be able to connect to the internet via data and thus will not be able to play Pokemon Go.
3. Restart/reset your phone. Try turning it off and turning it back on again.
4. Try deleting the app and reinstalling it. Fortunately, the app data is stored in Niantic's servers, so deleting the app doesn't actually delete any of your game's progress. You can reinstall it and sign in with the same Pokemon Go account.
5. Just try again later. As with many issues with Pokemon Go, the Niantic servers are constantly under load due to the massive amount of hype this game has amassed. Your phone, for some odd reason, may be having issues connecting due to server issues, and if this is the case, you'll just have to be patient and try again later.
6. Browse Arqade for other answers. There are thousands of Pokemon Go questions on this site now and I'm sure that there are other people out there who are also having an issue similar to this (e.g. - Why can't I connect to Pokemon Go via mobile data? (credit to Tim))