Default Play Store 491 error and messenger notifications

Jus got a moto g 4g and pretty much straight away I was getting 491 error when trying to download apps. I googled it and found lots of supposed solutions like clearing play store app data and removing and re-adding google account but that hasn't fixed it. I sometimes still get a 491 error.

facebook messenger notifications are also a bit hit and miss. they will work for a bit then just stop. I tried clearing messenger app data and that sorted it out but then they stopped working a few hours later. I get a notification if the messenger app is open and i'm in a different conversation but outside of the app I get nothing. I'd rather not have to clear app data every time I get this problem as I have to set the app up again.

Any help would be appreciated.