Why the marker position was incorrect occasionally? - leaflet

Question

I'm new to Leaflet map, and I use the OpenStreetMap to show the device location, I confuse why occasionally I got the incorrect marker position for the same latitude and longitude? (it's very far away from the real location).
what did I miss?
my javasript codes below looks correct (I have double check it)
renderMap(-6.208763, 106.845599, address, 14);
var marker;
var deviceLocation;
var geoFencing;
function renderMap(lat, lon, address, zoom)
{
if ($('#device-location').length)
{
if (deviceLocation == undefined)
{
deviceLocation = L.map('device-location');
}
else
{
deviceLocation.off();
deviceLocation.remove();
deviceLocation = L.map('device-location');
}
var latLon = new L.LatLng(lat,lon)
console.log(latLon);
deviceLocation.setView(latLon, 14);
deviceLocation.locate({
watch: false,
setView: false,
timeout: 10000,
enableHighAccuracy: false
});
function onLocationFound(e)
{
var radius = e.accuracy;
//console.log(e.latlng + " " + radius);
marker = L.marker(e.latlng)
.addTo(deviceLocation)
.bindPopup((geoFenceFound ?
'<strong>Your device</strong> is somewhere around ' + radius + ' meters from this point.</br></br>'
))
.openPopup();
var circle = L.circle(e.latlng, radius).addTo(deviceLocation);
var LatLonBounds = circle.getBounds();
geoFencing = circle;
if (geoFenceFound)
deviceLocation.fitBounds(LatLonBounds);
}
function onLocationError(e)
{
showWarning(e.message);
}
function onZoomEnd(e)
{
if (marker != undefined)
{
console.log('onZoomEnd: ' + marker.getLatLng());
deviceLocation.panTo(marker.getLatLng());
}
}
function onResize(e)
{
if (marker != undefined)
{
console.log('onResize: ' + marker.getLatLng());
deviceLocation.panTo(marker.getLatLng());
}
}
deviceLocation.on('locationfound', onLocationFound);
deviceLocation.on('locationerror', onLocationError);
deviceLocation.on('zoomend', onZoomEnd);
deviceLocation.on('resize', onResize);
L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', {
maxZoom: 19,
attribution: '© OpenStreetMap'
}).addTo(deviceLocation);
}
}