Sharing .AspNet.ApplicationCookie between two MVC projects - asp.net-mvc

Question

I have a Web project to login our users. It signs a user in, creates the ".AspNet.ApplicationCookie" cookie and then redirects to a page "~/Views/../Redirect.cshtml" that will choose, based on some rules, what will be the Website user will be redirected to. Very simple, a "redirecting..." message and a setTimeout function.
The problem is...website 2 does not recognize cookie created by site 1 and just moves the user back to site 1.
Some information:
1 - Works running both sites locally
2 - Site 1 and 2 are in the same server running on the same domain, just different ports.
3 - Both sites share the same ApplicationUserManager.Create call since I moved this class to a Domain project.
Startup.cs is as follows:
public void ConfigureAuth(IAppBuilder app)
{
// Configure the db context, user manager and signin manager to use a single instance per request
app.CreatePerOwinContext(AccountDbContext.Create);
app.CreatePerOwinContext<ApplicationUserManager>(ApplicationUserManager.Create);
app.CreatePerOwinContext<ApplicationSignInManager>(ApplicationSignInManager.Create);
// Enable the application to use a cookie to store information for the signed in user
// and to use a cookie to temporarily store information about a user logging in with a third party login provider
// Configure the sign in cookie
app.UseCookieAuthentication(new CookieAuthenticationOptions
{
AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
LoginPath = new PathString("/Account/Login"),
Provider = new CookieAuthenticationProvider
{
// Enables the application to validate the security stamp when the user logs in.
// This is a security feature which is used when you change a password or add an external login to your account.
OnValidateIdentity = SecurityStampValidator.OnValidateIdentity<ApplicationUserManager, ApplicationUser>(
validateInterval: TimeSpan.FromMinutes(30),
regenerateIdentity: (manager, user) => user.GenerateUserIdentityAsync(manager, DefaultAuthenticationTypes.ApplicationCookie))
}
});
app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);
// Enables the application to temporarily store user information when they are verifying the second factor in the two-factor authentication process.
app.UseTwoFactorSignInCookie(DefaultAuthenticationTypes.TwoFactorCookie, TimeSpan.FromMinutes(5));
// Enables the application to remember the second login verification factor such as phone or email.
// Once you check this option, your second step of verification during the login process will be remembered on the device where you logged in from.
// This is similar to the RememberMe option when you log in.
app.UseTwoFactorRememberBrowserCookie(DefaultAuthenticationTypes.TwoFactorRememberBrowserCookie);
}

Answer 1

It turns out that the problem was the Application Pool. All sites sharing the same cookie need to run on the same Application Pool. Once I set them all to use the same, it worked just fine.