Why is my 'What is My Location?' web tool showing inaccurate geolocation data for mobile users?

hey everyone, just launched our 'What is My Location?' tool and it's mostly great for finding current coordinates & map location. but we're seeing a weird problem with geolocation accuracy, especially for mobile users. desktop seems fine. it seems like the browser's geolocation API sometimes just times out or returns a very broad location, sometimes even a different city! like, way off. sometimes it's so off it feels like it's just guessing based on a very broad IP address range, not actual GPS. here's a snippet from our console when it acts up, it's either a permission thing or a timeout:

GeolocationPositionError: User denied geolocation permission. (code: 1)
  OR
GeolocationPositionError: Geolocation timed out. (code: 3)
  at <anonymous>:1:1

we've tried increasing timeout values and checking for HTTPS, obviusly, but no real luck. any ideas why our geolocation is so inconsistent on mobile? help a brother out please...