diff --git a/src/ZB.MOM.WW.ScadaBridge.Commons/Serialization/MxGatewayEndpointConfigSerializer.cs b/src/ZB.MOM.WW.ScadaBridge.Commons/Serialization/MxGatewayEndpointConfigSerializer.cs
new file mode 100644
index 00000000..40282828
--- /dev/null
+++ b/src/ZB.MOM.WW.ScadaBridge.Commons/Serialization/MxGatewayEndpointConfigSerializer.cs
@@ -0,0 +1,65 @@
+using System.Globalization;
+using System.Text.Json;
+using ZB.MOM.WW.ScadaBridge.Commons.Types.DataConnections;
+
+namespace ZB.MOM.WW.ScadaBridge.Commons.Serialization;
+
+/// <summary>
+/// Serializes <see cref="MxGatewayEndpointConfig"/> to/from the typed JSON stored in
+/// <c>DataConnection.PrimaryConfiguration</c> / <c>BackupConfiguration</c>, and flattens
+/// it to the <c>IDictionary&lt;string,string&gt;</c> shape <c>IDataConnection.ConnectAsync</c>
+/// expects. MxGateway is net-new, so there is no legacy shape to recover — a row that
+/// fails to parse yields a default config.
+/// </summary>
+public static class MxGatewayEndpointConfigSerializer
+{
+    private static readonly JsonSerializerOptions JsonOpts = new()
+    {
+        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+        WriteIndented = false,
+    };
+
+    /// <summary>Serializes a config to the typed JSON shape.</summary>
+    /// <param name="config">The endpoint configuration to serialize.</param>
+    public static string Serialize(MxGatewayEndpointConfig config)
+        => JsonSerializer.Serialize(config, JsonOpts);
+
+    /// <summary>Parses stored config JSON; null/blank/malformed yields a default config.</summary>
+    /// <param name="json">The stored JSON string.</param>
+    public static MxGatewayEndpointConfig Deserialize(string? json)
+    {
+        if (string.IsNullOrWhiteSpace(json)) return new MxGatewayEndpointConfig();
+        try { return JsonSerializer.Deserialize<MxGatewayEndpointConfig>(json, JsonOpts) ?? new MxGatewayEndpointConfig(); }
+        catch (JsonException) { return new MxGatewayEndpointConfig(); }
+    }
+
+    /// <summary>Flattens the typed config to the key-value shape the adapter consumes.</summary>
+    /// <param name="c">The endpoint configuration to flatten.</param>
+    public static IDictionary<string, string> ToFlatDict(MxGatewayEndpointConfig c) => new Dictionary<string, string>
+    {
+        ["Endpoint"] = c.Endpoint,
+        ["ApiKey"] = c.ApiKey,
+        ["ClientName"] = c.ClientName,
+        ["WriteUserId"] = c.WriteUserId.ToString(CultureInfo.InvariantCulture),
+        ["UseTls"] = c.UseTls.ToString(),
+        ["CaFile"] = c.CaFile,
+        ["ServerName"] = c.ServerName,
+        ["ReadTimeoutMs"] = c.ReadTimeoutMs.ToString(CultureInfo.InvariantCulture),
+    };
+
+    /// <summary>Reconstructs a config from the flat key-value shape; invalid numerics fall back to defaults.</summary>
+    /// <param name="d">The flat dictionary.</param>
+    public static MxGatewayEndpointConfig FromFlatDict(IDictionary<string, string> d)
+    {
+        var c = new MxGatewayEndpointConfig();
+        if (d.TryGetValue("Endpoint", out var ep) && !string.IsNullOrWhiteSpace(ep)) c.Endpoint = ep;
+        if (d.TryGetValue("ApiKey", out var ak)) c.ApiKey = ak;
+        if (d.TryGetValue("ClientName", out var cn)) c.ClientName = cn;
+        if (d.TryGetValue("WriteUserId", out var wu) && int.TryParse(wu, out var wuv)) c.WriteUserId = wuv;
+        if (d.TryGetValue("UseTls", out var tls) && bool.TryParse(tls, out var tlsv)) c.UseTls = tlsv;
+        if (d.TryGetValue("CaFile", out var ca)) c.CaFile = ca;
+        if (d.TryGetValue("ServerName", out var sn)) c.ServerName = sn;
+        if (d.TryGetValue("ReadTimeoutMs", out var rt) && int.TryParse(rt, out var rtv)) c.ReadTimeoutMs = rtv;
+        return c;
+    }
+}
diff --git a/tests/ZB.MOM.WW.ScadaBridge.Commons.Tests/Types/DataConnections/MxGatewayEndpointConfigSerializerTests.cs b/tests/ZB.MOM.WW.ScadaBridge.Commons.Tests/Types/DataConnections/MxGatewayEndpointConfigSerializerTests.cs
new file mode 100644
index 00000000..2493111c
--- /dev/null
+++ b/tests/ZB.MOM.WW.ScadaBridge.Commons.Tests/Types/DataConnections/MxGatewayEndpointConfigSerializerTests.cs
@@ -0,0 +1,84 @@
+using ZB.MOM.WW.ScadaBridge.Commons.Serialization;
+using ZB.MOM.WW.ScadaBridge.Commons.Types.DataConnections;
+
+namespace ZB.MOM.WW.ScadaBridge.Commons.Tests.Types.DataConnections;
+
+public class MxGatewayEndpointConfigSerializerTests
+{
+    [Fact]
+    public void Serialize_then_Deserialize_round_trips_all_fields()
+    {
+        var original = new MxGatewayEndpointConfig
+        {
+            Endpoint = "https://gw:5001",
+            ApiKey = "secret-key",
+            ClientName = "client-a",
+            WriteUserId = 7,
+            UseTls = true,
+            CaFile = "/certs/ca.pem",
+            ServerName = "gw.local",
+            ReadTimeoutMs = 1234
+        };
+
+        var json = MxGatewayEndpointConfigSerializer.Serialize(original);
+        var round = MxGatewayEndpointConfigSerializer.Deserialize(json);
+
+        Assert.Equal(original.Endpoint, round.Endpoint);
+        Assert.Equal(original.ApiKey, round.ApiKey);
+        Assert.Equal(original.ClientName, round.ClientName);
+        Assert.Equal(original.WriteUserId, round.WriteUserId);
+        Assert.Equal(original.UseTls, round.UseTls);
+        Assert.Equal(original.CaFile, round.CaFile);
+        Assert.Equal(original.ServerName, round.ServerName);
+        Assert.Equal(original.ReadTimeoutMs, round.ReadTimeoutMs);
+    }
+
+    [Theory]
+    [InlineData(null)]
+    [InlineData("")]
+    [InlineData("   ")]
+    [InlineData("{ not valid json")]
+    public void Deserialize_null_blank_or_malformed_returns_default(string? json)
+    {
+        var def = new MxGatewayEndpointConfig();
+        var result = MxGatewayEndpointConfigSerializer.Deserialize(json);
+        Assert.Equal(def.Endpoint, result.Endpoint);
+        Assert.Equal(def.ReadTimeoutMs, result.ReadTimeoutMs);
+    }
+
+    [Fact]
+    public void ToFlatDict_FromFlatDict_round_trips()
+    {
+        var original = new MxGatewayEndpointConfig
+        {
+            Endpoint = "http://x:5000",
+            ApiKey = "k",
+            ClientName = "c",
+            WriteUserId = 3,
+            UseTls = true,
+            CaFile = "/ca",
+            ServerName = "s",
+            ReadTimeoutMs = 999
+        };
+
+        var dict = MxGatewayEndpointConfigSerializer.ToFlatDict(original);
+        var round = MxGatewayEndpointConfigSerializer.FromFlatDict(dict);
+
+        Assert.Equal(original.Endpoint, round.Endpoint);
+        Assert.Equal(original.ApiKey, round.ApiKey);
+        Assert.Equal(original.ClientName, round.ClientName);
+        Assert.Equal(original.WriteUserId, round.WriteUserId);
+        Assert.Equal(original.UseTls, round.UseTls);
+        Assert.Equal(original.CaFile, round.CaFile);
+        Assert.Equal(original.ServerName, round.ServerName);
+        Assert.Equal(original.ReadTimeoutMs, round.ReadTimeoutMs);
+    }
+
+    [Fact]
+    public void FromFlatDict_invalid_numeric_falls_back_to_default()
+    {
+        var back = MxGatewayEndpointConfigSerializer.FromFlatDict(
+            new Dictionary<string, string> { ["ReadTimeoutMs"] = "not-a-number" });
+        Assert.Equal(new MxGatewayEndpointConfig().ReadTimeoutMs, back.ReadTimeoutMs);
+    }
+}