Use ProtectedSessionStorage to for add server wizard.

And replace the URL query string with it.

ServerManagement/Components/Pages/Wizards/SetCityName.razor

@@ -1,6 +1,9 @@
 @page "/cityname"
 
+@using ServerManagement.StateStore
+
 @inject NavigationManager NavigationManager
+@inject SessionStorage sessionStorage
 
 <h3>City Name</h3>
 <br/>
@@ -12,17 +15,20 @@
   </div>
 }
 
+@if (server != null)
+{
   <FieldComponent Label="City name">
     <Control>
-    <input type="text" @bind-value="cityName" class="form-control"></input>
+      <input type="text" @bind-value="server.City" class="form-control"></input>
     </Control>
   </FieldComponent>
   <br/>
   <button type="button" class="btn btn-primary" @onclick="GoNext">Next</button>
+}
 
 @code {
+  private Server? server;
   private string? errorMessage;
-  private string? cityName;
 
   [SupplyParameterFromQuery]
   private string? ServerName { get; set; }
@@ -32,31 +38,28 @@
     base.OnInitialized();
   }
 
-  protected override void OnAfterRender(bool firstRender)
+  protected override async Task OnAfterRenderAsync(bool firstRender)
   {
     if (firstRender)
     {
-      if (string.IsNullOrWhiteSpace(ServerName))
-      {
-        this.errorMessage = "Server name was not provided.";
+      this.server = await sessionStorage.GetServerAsync();
       StateHasChanged();
     }
   }
-  }
 
-  private void GoNext()
+  private async Task GoNext()
   {
-    if (string.IsNullOrWhiteSpace(ServerName))
+    if (server != null)
     {
-      this.errorMessage = "Server name is required.";
-      return;
-    }
-    if (string.IsNullOrWhiteSpace(cityName))
+      if (string.IsNullOrWhiteSpace(server.City))
       {
         this.errorMessage = "City name is required.";
-      return;
       }
-    
-    NavigationManager.NavigateTo($"/serverstatus?servername={ServerName}&cityname={cityName}");    
+      else
+      {
+        await this.sessionStorage.SetServerAsync(server);
+        NavigationManager.NavigateTo($"/serverstatus");
+      }
+    }
   }
 }

ServerManagement/Components/Pages/Wizards/SetServerName.razor

@@ -1,6 +1,9 @@
 @page "/servername"
 
+@using ServerManagement.StateStore
+
 @inject NavigationManager NavigationManager
+@inject SessionStorage sessionStorage
 
 <h3>Server Name</h3>
 <br/>
@@ -12,31 +15,45 @@
   </div>
 }
 
+@if (server != null)
+{
   <FieldComponent Label="Server name">
     <Control>
-    <input type="text" @bind-value="serverName" class="form-control"></input>
+      <input type="text" @bind-value="server.Name" class="form-control"></input>
     </Control>
   </FieldComponent>
   <br/>
   <button type="button" class="btn btn-primary" @onclick="GoNext">Next</button>
+}
 
 @code {
+  private Server? server;
   private string? errorMessage;
-  private string? serverName;
 
   protected override void OnInitialized()
   {
     base.OnInitialized();
   }
 
-  private void GoNext()
+  protected override void OnAfterRender(bool firstRender)
   {
-    if (string.IsNullOrWhiteSpace(serverName))
+    if (firstRender)
     {
-      this.errorMessage = "Server name is required.";
-      return;
+      server = new Server();
+      StateHasChanged();
+    }
   }
 
-    NavigationManager.NavigateTo($"/cityname?servername={serverName}");    
+  private async Task GoNext()
+  {
+    if (string.IsNullOrWhiteSpace(server?.Name))
+    {
+      this.errorMessage = "Server name is required.";
+    }
+    else
+    {
+      await sessionStorage.SetServerAsync(server);
+      NavigationManager.NavigateTo($"/cityname");
+    }
   }
 }

ServerManagement/Components/Pages/Wizards/SetStatus.razor

@@ -1,76 +1,55 @@
 @page "/serverstatus"
 
+@using ServerManagement.StateStore
+
 @inject NavigationManager NavigationManager
+@inject SessionStorage sessionStorage
 
 <h3>Server Status</h3>
 <br/>
 
-@if (!string.IsNullOrWhiteSpace(errorMessage))
+@if (server != null)
 {
-  <div class="alert alert-danger">
-    @errorMessage
-  </div>
-}
-
   <FieldComponent Label="Server status online">
     <Control>
-    <input type="checkbox" @bind-value="isOnline" class="form-check-input"></input>
+      @if (server.IsOnline)
+      {
+        <input type="checkbox" @bind-value="server.IsOnline" class="form-check-input"></input>
+      }
+      else
+      {
+        <input type="checkbox" @bind-value="server.IsOnline" class="form-check-input" checked></input>
+      }
     </Control>
   </FieldComponent>
   <br/>
   <button type="button" class="btn btn-primary" @onclick="Save">Save</button>
+}
 
 @code {
-  private string? errorMessage;
-  private bool isOnline;
-  [SupplyParameterFromQuery]
-  private string? CityName { get; set; }
-
-  [SupplyParameterFromQuery]
-  private string? ServerName { get; set; }
+  private Server? server;
 
   protected override void OnInitialized()
   {
     base.OnInitialized();
   }
 
-  protected override void OnAfterRender(bool firstRender)
+  protected override async Task OnAfterRenderAsync(bool firstRender)
   {
     if (firstRender)
     {
-      if (string.IsNullOrWhiteSpace(ServerName))
-      {
-        this.errorMessage = "Server name was not provided.";
-        StateHasChanged();
-      }
-      else if (string.IsNullOrWhiteSpace(CityName))
-      {
-        this.errorMessage = "City name was not provided.";
+      this.server = await sessionStorage.GetServerAsync();
       StateHasChanged();
     }
   }
-  }
 
-  private void Save()
+  private async Task Save()
   {
-    if (string.IsNullOrWhiteSpace(ServerName))
+    if (server != null)
     {
-      this.errorMessage = "Server name is required.";
-      return;
-    }
-    if (string.IsNullOrWhiteSpace(CityName))
-    {
-      this.errorMessage = "City name is required.";
-      return;
-    }    
-
-    var server = new Server
-    {
-      Name = this.ServerName,
-      City = this.CityName,
-      IsOnline = this.isOnline
-    };
+      await sessionStorage.SetServerAsync(null);
       ServersRepository.AddServer(server);
-    NavigationManager.NavigateTo($"/servers/back_from/{CityName}");    
+      NavigationManager.NavigateTo($"/servers/back_from/{server?.City}");
+    }
   }
 }

ServerManagement/Components/StateStore/SessionStorage.cs

@@ -0,0 +1,33 @@
+using Microsoft.AspNetCore.Components.Server.ProtectedBrowserStorage;
+using ServerManagement.Models;
+
+namespace ServerManagement.StateStore
+{
+  public class SessionStorage
+  {
+    private readonly ProtectedSessionStorage protectedSessionStorage;
+
+    public SessionStorage(ProtectedSessionStorage protectedSessionStorage)
+    {
+      this.protectedSessionStorage = protectedSessionStorage;
+    }
+
+    public async Task<Server?> GetServerAsync()
+    {
+      var result = await this.protectedSessionStorage.GetAsync<Server>("server");
+      if (result.Success)
+      {
+        return result.Value;
+      }
+      else
+      {
+        return null;
+      }
+    }
+
+    public async Task SetServerAsync(Server? server)
+    {
+      await this.protectedSessionStorage.SetAsync("server", server);
+    }
+  }
+}

ServerManagement/Components/_Imports.razor

@@ -11,3 +11,4 @@
 @using ServerManagement.Components.Controls
 @using ServerManagement.Components.Controls.Generic
 @using ServerManagement.Models
+@using ServerManagement.StateStore

ServerManagement/Program.cs

@@ -1,4 +1,5 @@
 using ServerManagement.Components;
+using ServerManagement.StateStore;
 
 var builder = WebApplication.CreateBuilder(args);
 
@@ -6,6 +7,8 @@ var builder = WebApplication.CreateBuilder(args);
 builder.Services.AddRazorComponents()
     .AddInteractiveServerComponents(); // Provides server interactivity.
 
+builder.Services.AddTransient<SessionStorage>();
+
 var app = builder.Build();
 
 // Configure the HTTP request pipeline.