InProc Session for ASP.NET CORE MVC not working on IIS - session

Question

I am looking for help and advice regarding session state(InProc) is null when asp.net core mvc 6.0 is hosted on IIS.
I have read a number of blogs but those solutions suggested do not seem to be working to me.
Session state working fine when my web app is launched with ipaddress + port(other than 80) but broken when browse with registered domain name.
What mistake I have done?
I have attach my codes for your reference. Do let me know if you need further info.
// Program.cs
builder.Services.ConfigureAntiforgeryOptions();
builder.Services.AddControllersWithViews()
.AddCookieTempDataProvider();
builder.Services.ConfigureIocScanOptions();
builder.Services.AddSession(options => {
options.IdleTimeout = TimeSpan.FromMinutes(10);
options.Cookie.Name = ".WebApp.Session";
options.Cookie.HttpOnly = true;
options.Cookie.IsEssential = true;
});
builder.Services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
var app = builder.Build();
// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
app.UseExceptionHandler("/Home/Error");
app.UseHsts();
}
else
{
app.UseDeveloperExceptionPage();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseSession();
app.MapControllerRoute(
name: "default",
pattern: "{controller=Auth}/{action=Index}/{id?}");
app.Run();
// Extension to set and get session variable value
public static class SessionExtensions
{
public static void Set<T>(this ISession session, string key, T value)
{
session.SetString(key, JsonSerializer.Serialize(value));
}
public static T? Get<T>(this ISession session, string key)
{
var value = session.GetString(key);
return value == null ? default : JsonSerializer.Deserialize<T>(value);
}
}