diff --git a/src/ZB.MOM.WW.ScadaBridge.Commons/Validators/MxGatewayEndpointConfigValidator.cs b/src/ZB.MOM.WW.ScadaBridge.Commons/Validators/MxGatewayEndpointConfigValidator.cs
new file mode 100644
index 00000000..8443e77d
--- /dev/null
+++ b/src/ZB.MOM.WW.ScadaBridge.Commons/Validators/MxGatewayEndpointConfigValidator.cs
@@ -0,0 +1,46 @@
+using ZB.MOM.WW.ScadaBridge.Commons.Types.DataConnections;
+using ZB.MOM.WW.ScadaBridge.Commons.Types.Flattening;
+
+namespace ZB.MOM.WW.ScadaBridge.Commons.Validators;
+
+/// <summary>
+/// Pure-function validator for <see cref="MxGatewayEndpointConfig"/>. Errors carry
+/// the offending property name in <see cref="ValidationEntry.EntityName"/>
+/// (optionally prefixed, e.g. "Primary.Endpoint") so the form can render
+/// per-field messages.
+/// </summary>
+public static class MxGatewayEndpointConfigValidator
+{
+    /// <summary>
+    /// Validates all fields of an <see cref="MxGatewayEndpointConfig"/>, returning errors with optionally-prefixed field names.
+    /// </summary>
+    /// <param name="config">The MxGateway endpoint configuration to validate.</param>
+    /// <param name="fieldPrefix">Optional prefix prepended to each field name in error entries (e.g., "Primary.").</param>
+    public static ValidationResult Validate(MxGatewayEndpointConfig config, string fieldPrefix = "")
+    {
+        var errors = new List<ValidationEntry>();
+
+        if (string.IsNullOrWhiteSpace(config.Endpoint))
+            errors.Add(Err("Endpoint", "Endpoint URL is required."));
+        else if (!Uri.TryCreate(config.Endpoint, UriKind.Absolute, out var uri)
+                 || (uri.Scheme != "http" && uri.Scheme != "https")
+                 || string.IsNullOrEmpty(uri.Host))
+            errors.Add(Err("Endpoint", "Endpoint URL must be a valid http:// or https:// URI."));
+
+        if (string.IsNullOrWhiteSpace(config.ApiKey))
+            errors.Add(Err("ApiKey", "API key is required."));
+
+        if (config.ReadTimeoutMs <= 0)
+            errors.Add(Err("ReadTimeoutMs", "Must be > 0."));
+
+        return errors.Count == 0
+            ? ValidationResult.Success()
+            : ValidationResult.FromErrors(errors.ToArray());
+
+        ValidationEntry Err(string field, string message) =>
+            ValidationEntry.Error(
+                ValidationCategory.ConnectionConfig,
+                message,
+                entityName: $"{fieldPrefix}{field}");
+    }
+}
diff --git a/tests/ZB.MOM.WW.ScadaBridge.Commons.Tests/Validators/MxGatewayEndpointConfigValidatorTests.cs b/tests/ZB.MOM.WW.ScadaBridge.Commons.Tests/Validators/MxGatewayEndpointConfigValidatorTests.cs
new file mode 100644
index 00000000..0813132a
--- /dev/null
+++ b/tests/ZB.MOM.WW.ScadaBridge.Commons.Tests/Validators/MxGatewayEndpointConfigValidatorTests.cs
@@ -0,0 +1,77 @@
+using ZB.MOM.WW.ScadaBridge.Commons.Types.DataConnections;
+using ZB.MOM.WW.ScadaBridge.Commons.Types.Flattening;
+using ZB.MOM.WW.ScadaBridge.Commons.Validators;
+
+namespace ZB.MOM.WW.ScadaBridge.Commons.Tests.Validators;
+
+public class MxGatewayEndpointConfigValidatorTests
+{
+    private static MxGatewayEndpointConfig Valid() => new()
+    {
+        Endpoint = "http://gw:5000",
+        ApiKey = "key",
+    };
+
+    [Fact]
+    public void Validate_ValidConfig_IsValid()
+    {
+        var result = MxGatewayEndpointConfigValidator.Validate(Valid());
+        Assert.True(result.IsValid);
+        Assert.Empty(result.Errors);
+    }
+
+    [Fact]
+    public void Validate_MissingEndpoint_Fails()
+    {
+        var c = Valid();
+        c.Endpoint = "";
+        var r = MxGatewayEndpointConfigValidator.Validate(c);
+        Assert.False(r.IsValid);
+        Assert.Contains(r.Errors, e =>
+            e.EntityName == "Endpoint"
+            && e.Category == ValidationCategory.ConnectionConfig
+            && e.Message.Contains("required", StringComparison.OrdinalIgnoreCase));
+    }
+
+    [Theory]
+    [InlineData("opc.tcp://x:4840")]
+    [InlineData("ftp://x")]
+    [InlineData("not a url")]
+    public void Validate_BadEndpointScheme_Fails(string url)
+    {
+        var c = Valid();
+        c.Endpoint = url;
+        var r = MxGatewayEndpointConfigValidator.Validate(c);
+        Assert.False(r.IsValid);
+        Assert.Contains(r.Errors, e => e.EntityName == "Endpoint");
+    }
+
+    [Fact]
+    public void Validate_MissingApiKey_Fails()
+    {
+        var c = Valid();
+        c.ApiKey = "";
+        var r = MxGatewayEndpointConfigValidator.Validate(c);
+        Assert.False(r.IsValid);
+        Assert.Contains(r.Errors, e => e.EntityName == "ApiKey");
+    }
+
+    [Fact]
+    public void Validate_NonPositiveReadTimeout_Fails()
+    {
+        var c = Valid();
+        c.ReadTimeoutMs = 0;
+        var r = MxGatewayEndpointConfigValidator.Validate(c);
+        Assert.False(r.IsValid);
+        Assert.Contains(r.Errors, e => e.EntityName == "ReadTimeoutMs");
+    }
+
+    [Fact]
+    public void Validate_PrefixedFieldNames_AppearInErrors()
+    {
+        var c = Valid();
+        c.Endpoint = "";
+        var r = MxGatewayEndpointConfigValidator.Validate(c, "Primary.");
+        Assert.Contains(r.Errors, e => e.EntityName == "Primary.Endpoint");
+    }
+}