I suspect it's the garmin connect app itself because at the same time my Fenix5 also stopped getting weather updates.
I tried changing from "phone location" to "fixed location" (and back) but it doesn't fix anything.
Not really anything you can adjust on the vivosmart4, how do I fix this? Is there a FAQ somewhere?
Note that everything else works including messages from the phone, data updates, etc. via bluetooth, it's not a bluetooth problem.
Garmin seems to have an endless problem with their weather service on their devices.