Also getting error 404 with makeImageRequest :-(

Using SDK 8.1.1 on both a simulated Fenix 7S Pro and Edge 840, using URL http://weewx.{my_host_name}.duckdns.org/daywindvec.png for makeImageRequest gives me a 404 error. Reading the same URL from my phone disconnected from my home WiFi (ie, getting the image like Garmin's servers would, outside of my home network) results in said image fetched so it's not because the file isn't externally accessible. Using URL http://static.garmincdn.com/com.garmin/ui/images/logo/garmin_logo_on_w.png fetches the image so my makeImageRequest call is correctly coded (see below). Looking at my web server log file, I see no attempt to fetch that file from Garmin's web server and I do see the fetch from my cell so I'm looking at the right place.

Anything I can do on my side to successfully get that file? Here's the code snippet of said call

    var url = "http://weewx.{my_host_name}.duckdns.org/daywindvec.png"; /*"http://static.garmincdn.com/com.garmin/ui/images/logo/garmin_logo_on_w.png";*/
    var params = null;

    var options = {
        :palette => [
            Gfx.COLOR_WHITE,
            Gfx.COLOR_GREEN,
            Gfx.COLOR_DK_GREEN,
            Gfx.COLOR_LT_GRAY,
            Gfx.COLOR_DK_GRAY,
            Gfx.COLOR_BLACK
        ],
        :maxWidth => 127,
        :maxHeight => 127,
        :dithering => Comm.IMAGE_DITHERING_NONE,
        :packingFormat => Comm.PACKING_FORMAT_PNG
    };

    Comm.makeImageRequest(url, params, options, method(:onImageResponse));

Thanks