The first thing I would inspect is the browser’s network trace. I.e, which requests and responses are going on. You might be able to derive from the trace whether the problem is on the browser’s end or at the server side.
(Especially if curl works fine then I would guess it is a browser problem.)
Thanks, the Network calls show the problem, it turns out that browser calls extra for favicon.ico,
it is a problem, and i found suggest how to get round it.
This extra GO code prevent it.
// ==> Dummy needed to stop browser to call extra times.
http.HandleFunc("/favicon.ico", func(w http.ResponseWriter, r *http.Request) {
})