Trouble with Favicon.ico not being displayed

[Tech500]

Code for favicon.ico request:

 serverAsync.on("/favicon.ico", HTTP_GET, [](AsyncWebServerRequest *request){
   request->send(LittleFS, "/favicon.ico", "image/x-icon");
});

If LAN address is used or WAN address is used Favicon.ico is displayed in Browser.

If No-ip.com; masked, URL record and hostname is used, Favicon.ico is not displayed in browser.

"weather-3.ddns.net" is the No-ip.com hostname.

William