diff --git a/BTCPayServer/Services/BTCPayServerEnvironment.cs b/BTCPayServer/Services/BTCPayServerEnvironment.cs
index a8e5d1105..bdcb187d9 100644
--- a/BTCPayServer/Services/BTCPayServerEnvironment.cs
+++ b/BTCPayServer/Services/BTCPayServerEnvironment.cs
@@ -7,13 +7,17 @@ using System.Threading.Tasks;
 using System.Text;
 using NBXplorer;
 using NBitcoin;
+using Microsoft.AspNetCore.Http;
 
 namespace BTCPayServer.Services
 {
     public class BTCPayServerEnvironment
     {
-        public BTCPayServerEnvironment(IHostingEnvironment env, BTCPayNetworkProvider provider)
+        public BTCPayServerEnvironment(IHostingEnvironment env, BTCPayNetworkProvider provider, IHttpContextAccessor httpContext)
         {
+            ExpectedHost = httpContext.HttpContext.Request.Host.Value;
+            ExpectedDomain = httpContext.HttpContext.Request.Host.Host;
+            ExpectedProtocol = httpContext.HttpContext.Request.Scheme;
             Version = typeof(BTCPayServerEnvironment).GetTypeInfo().Assembly.GetCustomAttribute<AssemblyFileVersionAttribute>().Version;
 #if DEBUG
             Build = "Debug";
@@ -27,6 +31,11 @@ namespace BTCPayServer.Services
         {
             get; set;
         }
+
+        public string ExpectedDomain { get; set; }
+        public string ExpectedHost { get; set; }
+        public string ExpectedProtocol { get; set; }
+
         public NetworkType NetworkType { get; set; }
         public string Version
         {
diff --git a/BTCPayServer/Views/Shared/_Layout.cshtml b/BTCPayServer/Views/Shared/_Layout.cshtml
index 2af9e84cd..98d4d44bf 100644
--- a/BTCPayServer/Views/Shared/_Layout.cshtml
+++ b/BTCPayServer/Views/Shared/_Layout.cshtml
@@ -78,9 +78,19 @@
 
                 </ul>
             </div>
+            <div id="badUrl" class="alert alert-danger alert-dismissible" style="display:none; position:absolute; top:75px;" role="alert">
+                <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">&times;</span></button>
+                <span>BTCPay is expecting you to access this website from <b>@(env.ExpectedProtocol)://@(env.ExpectedHost)/</b>. If you want to change this expectation:</span>
+                <ul>
+                    <li>Either starts BTCPay with <b>--externalurl @(env.ExpectedProtocol)://@(env.ExpectedHost)/</b></li>
+                    <li>Or, if using docker-compose deployment, setting environment variable <b>BTCPAY_PROTOCOL=@(env.ExpectedProtocol)</b> and <b>BTCPAY_HOST=@(env.ExpectedDomain)</b></li>
+                </ul>
+                
+            </div>
         </div>
     </nav>
 
+
     @RenderBody()
 
     <footer class="siteFooter bg-dark text-white">
@@ -93,6 +103,14 @@
     }
 
     @RenderSection("Scripts", required: false)
+
+    <script type="text/javascript">
+        var expectedDomain = @Html.Raw(Json.Serialize(env.ExpectedHost));
+        var expectedProtocol = @Html.Raw(Json.Serialize(env.ExpectedProtocol));
+        if (window.location.host != expectedDomain || window.location.protocol != expectedProtocol + ":") {
+            document.getElementById("badUrl").style.display = "block";
+        }
+    </script>
 </body>
 
 </html>