System.ObjectDisposedException: 'The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.'2022 – Asp.net

Im doing a MVC app but when I try to run it, it shows the following errors

System.ObjectDisposedException: ‘The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.’
item.Plan.Plan_Days = ‘item.Plan.Plan_Days’ threw an exception of type ‘System.NullReferenceException’

@model IEnumerable<POS.Models.Faculty>

@{
    ViewBag.Title = "Index";
}

<h2>Index</h2>

<p>
    @Html.ActionLink("Crear Nuevo", "Guardar")
</p>
<table class="table">
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.Organization_Name)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.First_Name)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Last_Name)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Job_Title)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Email)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Photo)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Address)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Phone_Number)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Meal_Plan_Status)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Plan.Plan_Days)
        </th>
        <th></th>
    </tr>

@foreach (var item in Model) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.Organization_Name)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.First_Name)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Last_Name)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Job_Title)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Email)
        </td>
        <td>
            <img src=" @Html.DisplayFor(modelItem => item.Photo)" width="200" />
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Address)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Phone_Number)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Meal_Plan_Status)
        </td>
        <<td>
            @Html.DisplayFor(modelItem => item.Plan.Plan_Days)
        </td>
        <td>
            @Html.ActionLink("Edit", "Edit", new { id=item.Employee_ID }) |
            @Html.ActionLink("Details", "Details", new { id=item.Employee_ID }) |
            @Html.ActionLink("Delete", "Delete", new { id=item.Employee_ID })
        </td>
    </tr>
}

</table>

This is the controller:

using POS.Datos;
using POS.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace POS.Controllers
{
    public class FacultyController : Controller
    {
        FacultyAdmin admin = new FacultyAdmin();

        // GET: Faculty
        public ActionResult Index()
        {
            return View(admin.Consultar());
        }

        public ActionResult Guardar()
        {
            ViewBag.mensaje = "";
            return View(); 
        }

        public ActionResult Nuevo(Faculty modelo)
        {
            admin.Guardar(modelo);
            ViewBag.mensaje = "Informacion Guardada";
            return View("Guardar",modelo);
        }
    }
}

Code of FacultyAdmin.cs:

using POS.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace POS.Datos
{
    public class FacultyAdmin
    {
        public void Guardar(Faculty modelo)
        {
           using (Cafeteria_POSEntities context = new Cafeteria_POSEntities())
            {
                context.Faculties.Add(modelo);
                context.SaveChanges();  
            }
        }

        public IEnumerable<Faculty>Consultar()
        {
            using (Cafeteria_POSEntities context = new Cafeteria_POSEntities())
            {
                return context.Faculties.AsNoTracking().ToList(); //AsNoTracking para no hacer copia en  memoria porque no se hace ningun CRUD 
            }
        }
    }
}

Faculties definition:

// <auto-generated>
//     This code was generated from a template.
//
//     Manual changes to this file may cause unexpected behavior in your application.
//     Manual changes to this file will be overwritten if the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------
    
using System;
using System.ComponentModel.DataAnnotations;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;

namespace POS.Models
{
    
    public partial class Cafeteria_POSEntities : DbContext
    {
        public Cafeteria_POSEntities()
            : base("name=Cafeteria_POSEntities")
        {
        }
    
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            throw new UnintentionalCodeFirstException();
        }
    
        public virtual DbSet<Faculty> Faculties { get; set; }
        public virtual DbSet<KU_Students> KU_Students { get; set; }
        public virtual DbSet<Language_Students> Language_Students { get; set; }
        public virtual DbSet<Menu> Menus { get; set; }
        public virtual DbSet<Order> Orders { get; set; }
        public virtual DbSet<Plan> Plans { get; set; }
        public virtual DbSet<Station> Stations { get; set; }
        public virtual DbSet<sysdiagram> sysdiagrams { get; set; }
    }
}