I've created these two users in my admin database:
db.auth('admin','password')
1
> db.getUsers()
[
    {
        "_id" : "admin.siteUserAdmin",
        "user" : "siteUserAdmin",
        "db" : "admin",
        "roles" : [
            {
                "role" : "userAdminAnyDatabase",
                "db" : "admin"
            }
        ]
    },
    {
        "_id" : "admin.admin",
        "user" : "admin",
        "db" : "admin",
        "roles" : [
            {
                "role" : "userAdminAnyDatabase",
                "db" : "admin"
            }
        ]
    }
]
I am uthenticated correctly from my localhost, but when I try to use an external client to get connected to my database I got this error:
Failed to authenticate admin@admin with mechanism MONGODB-CR: AuthenticationFailed MONGODB-CR credentials missing in the user document
How do I fix it?
 
     
    