Signin page redirect to 404 when first load vue js 2.0

When the application starts, I am setting the default path to users, if authentication fails, then it will navigate to sign in. But it redirects to 404.

const routes = [
{
  path: "/signin",
  name: "signIn",
  component: () => import("@/path"),
},
{
 .........
},
{
  .......
},
{
  path: "/",
  redirect: "/users",
  component: adminLayout,
  //needed for nav gaurd
  //meta: { requiresAuth: true },
  children: [
    {
      path: "dashboard",
      name: "dashboard",
      component: dashboard,
      meta: { 
        title: 'Dashbaord' 
      }
    },
    {
      path: "users",
      component: () => import("path"),
      meta: { 
        title: 'Users' 
      },
      children: [
        {
          path: "",
          component: () => import("path"),
          meta: { 
            title: ''
          }
        },
        {
          path: ":id/profile",
          component: () => import("path"),
          meta: { 
            title: 'Profile' 
          }
        },
      ]
    },
    
  ],
},
{
  path: "*",
  redirect: "/404",
},
{
  // the 404 route, when none of the above matches
  path: "/404",
  name: "404",
  component: () => import("@path"),
},

];

If i set redirect: "/dashboard" or redirect: "/signin",, then it works fine.
Also if I navigate to the right path, like "http://localhost:8080/signin" it will work. But if I only type "http://localhost:8080" hit enter it will go to 404 page

Note : first my users component like this and its works fine

{
        path: "users",
        component: () => import("path"),
        meta: { 
          title: 'Users' 
        },
},
{
        path: ":id/profile",
        component: () => import("path"),
        meta: { 
          title: 'Profile' 
        },
    },

Please help me to understand the issue.