From fa8f9e785a74f1aea8baa897a573adab7d1503c3 Mon Sep 17 00:00:00 2001
From: Nikolay Borisenko <22616990+nvborisenko@users.noreply.github.com>
Date: Wed, 20 Aug 2025 13:14:46 +0300
Subject: [PATCH 1/4] [dotnet] Fix find port for IPv4 only environments

---
 .../src/webdriver/Internal/PortUtilities.cs   | 28 ++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/dotnet/src/webdriver/Internal/PortUtilities.cs b/dotnet/src/webdriver/Internal/PortUtilities.cs
index a739e5ccd32f6..8ab2ebe45ba2d 100644
--- a/dotnet/src/webdriver/Internal/PortUtilities.cs
+++ b/dotnet/src/webdriver/Internal/PortUtilities.cs
@@ -33,10 +33,30 @@ public static class PortUtilities
     /// <returns>A random, free port to be listened on.</returns>
     public static int FindFreePort()
     {
-        using var socket = new Socket(AddressFamily.InterNetworkV6, SocketType.Stream, ProtocolType.Tcp);
-        socket.DualMode = true;
-        socket.Bind(new IPEndPoint(IPAddress.IPv6Loopback, 0));
-        return (socket.LocalEndPoint as IPEndPoint)!.Port;
+        // Prefer IPv6 dual-mode when available, but fall back robustly to IPv4
+        try
+        {
+            using var ipV6socket = new Socket(AddressFamily.InterNetworkV6, SocketType.Stream, ProtocolType.Tcp);
 
+            // Some platforms may not support DualMode or IPv6 at all; ignore failures and let bind decide
+            try
+            {
+                ipV6socket.DualMode = true;
+            }
+            catch
+            {
+                // Ignored; we'll still attempt to bind to IPv6 loopback
+            }
+
+            ipV6socket.Bind(new IPEndPoint(IPAddress.IPv6Loopback, 0));
+            return ((IPEndPoint)ipV6socket.LocalEndPoint!).Port;
+        }
+        catch(SocketException)
+        {
+            // If creating/binding the IPv6 socket fails for any reason, fall back to IPv4
+            using var ipV4socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+            ipV4socket.Bind(new IPEndPoint(IPAddress.Loopback, 0));
+            return ((IPEndPoint)ipV4socket.LocalEndPoint!).Port;
+        }
     }
 }

From 80190d829ac3a800ce5908df407d7e97c08ae7be Mon Sep 17 00:00:00 2001
From: Nikolay Borisenko <22616990+nvborisenko@users.noreply.github.com>
Date: Tue, 26 Aug 2025 21:26:23 +0300
Subject: [PATCH 2/4] Try ipv4 and fallback to ipv6

---
 .../src/webdriver/Internal/PortUtilities.cs   | 27 ++++++-------------
 1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/dotnet/src/webdriver/Internal/PortUtilities.cs b/dotnet/src/webdriver/Internal/PortUtilities.cs
index 8ab2ebe45ba2d..d7c1a3553fca3 100644
--- a/dotnet/src/webdriver/Internal/PortUtilities.cs
+++ b/dotnet/src/webdriver/Internal/PortUtilities.cs
@@ -33,30 +33,19 @@ public static class PortUtilities
     /// <returns>A random, free port to be listened on.</returns>
     public static int FindFreePort()
     {
-        // Prefer IPv6 dual-mode when available, but fall back robustly to IPv4
+        // Prefer IPv4, but fall back robustly to IPv6
         try
         {
-            using var ipV6socket = new Socket(AddressFamily.InterNetworkV6, SocketType.Stream, ProtocolType.Tcp);
-
-            // Some platforms may not support DualMode or IPv6 at all; ignore failures and let bind decide
-            try
-            {
-                ipV6socket.DualMode = true;
-            }
-            catch
-            {
-                // Ignored; we'll still attempt to bind to IPv6 loopback
-            }
-
-            ipV6socket.Bind(new IPEndPoint(IPAddress.IPv6Loopback, 0));
-            return ((IPEndPoint)ipV6socket.LocalEndPoint!).Port;
-        }
-        catch(SocketException)
-        {
-            // If creating/binding the IPv6 socket fails for any reason, fall back to IPv4
             using var ipV4socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
             ipV4socket.Bind(new IPEndPoint(IPAddress.Loopback, 0));
             return ((IPEndPoint)ipV4socket.LocalEndPoint!).Port;
         }
+        catch (SocketException)
+        {
+            // If creating/binding the IPv4 socket fails for any reason, fall back to IPv6
+            using var ipV6socket = new Socket(AddressFamily.InterNetworkV6, SocketType.Stream, ProtocolType.Tcp);
+            ipV6socket.Bind(new IPEndPoint(IPAddress.IPv6Loopback, 0));
+            return ((IPEndPoint)ipV6socket.LocalEndPoint!).Port;
+        }
     }
 }

From b6f22ffae6e68c41c3769d60ab6ffdcf03e34ed8 Mon Sep 17 00:00:00 2001
From: Nikolay Borisenko <22616990+nvborisenko@users.noreply.github.com>
Date: Tue, 26 Aug 2025 21:28:04 +0300
Subject: [PATCH 3/4] Update PortUtilities.cs

---
 dotnet/src/webdriver/Internal/PortUtilities.cs | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/dotnet/src/webdriver/Internal/PortUtilities.cs b/dotnet/src/webdriver/Internal/PortUtilities.cs
index d7c1a3553fca3..e07c18750a328 100644
--- a/dotnet/src/webdriver/Internal/PortUtilities.cs
+++ b/dotnet/src/webdriver/Internal/PortUtilities.cs
@@ -28,12 +28,11 @@ namespace OpenQA.Selenium.Internal;
 public static class PortUtilities
 {
     /// <summary>
-    /// Finds a random, free port to be listened on.
+    /// Finds a random, free port to be listened on. Prefers IPv4, but falls back to IPv6 if necessary.
     /// </summary>
     /// <returns>A random, free port to be listened on.</returns>
     public static int FindFreePort()
     {
-        // Prefer IPv4, but fall back robustly to IPv6
         try
         {
             using var ipV4socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
@@ -42,7 +41,6 @@ public static int FindFreePort()
         }
         catch (SocketException)
         {
-            // If creating/binding the IPv4 socket fails for any reason, fall back to IPv6
             using var ipV6socket = new Socket(AddressFamily.InterNetworkV6, SocketType.Stream, ProtocolType.Tcp);
             ipV6socket.Bind(new IPEndPoint(IPAddress.IPv6Loopback, 0));
             return ((IPEndPoint)ipV6socket.LocalEndPoint!).Port;

From 2114addd6a5165828d2fac3cf2f518db95a3f1d5 Mon Sep 17 00:00:00 2001
From: Nikolay Borisenko <22616990+nvborisenko@users.noreply.github.com>
Date: Tue, 26 Aug 2025 21:45:45 +0300
Subject: [PATCH 4/4] Move tech desription to remarks

---
 dotnet/src/webdriver/Internal/PortUtilities.cs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/dotnet/src/webdriver/Internal/PortUtilities.cs b/dotnet/src/webdriver/Internal/PortUtilities.cs
index e07c18750a328..6f67d5abbd4b6 100644
--- a/dotnet/src/webdriver/Internal/PortUtilities.cs
+++ b/dotnet/src/webdriver/Internal/PortUtilities.cs
@@ -28,8 +28,11 @@ namespace OpenQA.Selenium.Internal;
 public static class PortUtilities
 {
     /// <summary>
-    /// Finds a random, free port to be listened on. Prefers IPv4, but falls back to IPv6 if necessary.
+    /// Finds a random, free port to be listened on.
     /// </summary>
+    /// <remarks>
+    /// Prefers IPv4, but falls back to IPv6 if necessary.
+    /// </remarks>
     /// <returns>A random, free port to be listened on.</returns>
     public static int FindFreePort()
     {