diff --git a/src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.SslProtocols.cs b/src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.SslProtocols.cs
index ed0563692771c1..1d521de2f10165 100644
--- a/src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.SslProtocols.cs
+++ b/src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.SslProtocols.cs
@@ -127,7 +127,7 @@ public async Task GetAsync_AllowedSSLVersion_Succeeds(SslProtocols acceptedProto
                 }
 
                 // Use a different SNI for each connection to prevent TLS 1.3 renegotiation issue: https://github.com/dotnet/runtime/issues/47378
-                client.DefaultRequestHeaders.Host = getTestSNIName();
+                client.DefaultRequestHeaders.Host = GetTestSNIName();
 
                 var options = new LoopbackServer.Options { UseSsl = true, SslProtocols = acceptedProtocol };
                 await LoopbackServer.CreateServerAsync(async (server, url) =>
@@ -140,7 +140,7 @@ await TestHelper.WhenAllCompletedOrAnyFailed(
                 Assert.Equal(1, count);
             }
 
-            string getTestSNIName()
+            string GetTestSNIName()
             {
                 return $"{nameof(GetAsync_AllowedSSLVersion_Succeeds)}_{acceptedProtocol}_{requestOnlyThisProtocol}";
             }
diff --git a/src/libraries/System.Net.Security/tests/FunctionalTests/ClientAsyncAuthenticateTest.cs b/src/libraries/System.Net.Security/tests/FunctionalTests/ClientAsyncAuthenticateTest.cs
index b5770ef49de181..8ef2e170b69e81 100644
--- a/src/libraries/System.Net.Security/tests/FunctionalTests/ClientAsyncAuthenticateTest.cs
+++ b/src/libraries/System.Net.Security/tests/FunctionalTests/ClientAsyncAuthenticateTest.cs
@@ -145,10 +145,13 @@ private async Task ClientAsyncSslHelper(
             using (var client = new TcpClient())
             {
                 server.SslProtocols = serverSslProtocols;
+                // Use a different SNI for each connection to prevent TLS 1.3 renegotiation issue: https://github.com/dotnet/runtime/issues/47378
+                string serverName = TestHelper.GetTestSNIName(nameof(ClientAsyncSslHelper), clientSslProtocols, serverSslProtocols);
+
                 await client.ConnectAsync(server.RemoteEndPoint.Address, server.RemoteEndPoint.Port);
                 using (SslStream sslStream = new SslStream(client.GetStream(), false, certificateCallback != null ? certificateCallback : AllowAnyServerCertificate, null))
                 {
-                    Task clientAuthTask = sslStream.AuthenticateAsClientAsync("localhost", null, clientSslProtocols, false);
+                    Task clientAuthTask = sslStream.AuthenticateAsClientAsync(serverName, null, clientSslProtocols, false);
                     await clientAuthTask.TimeoutAfter(TestConfiguration.PassingTestTimeoutMilliseconds);
 
                     _log.WriteLine("Client authenticated to server({0}) with encryption cipher: {1} {2}-bit strength",
diff --git a/src/libraries/System.Net.Security/tests/FunctionalTests/ServerAsyncAuthenticateTest.cs b/src/libraries/System.Net.Security/tests/FunctionalTests/ServerAsyncAuthenticateTest.cs
index 5deb8334361863..4307b3df9d2751 100644
--- a/src/libraries/System.Net.Security/tests/FunctionalTests/ServerAsyncAuthenticateTest.cs
+++ b/src/libraries/System.Net.Security/tests/FunctionalTests/ServerAsyncAuthenticateTest.cs
@@ -362,7 +362,8 @@ private async Task ServerAsyncSslHelper(
                     return true;
                 }))
             {
-                string serverName = _serverCertificate.GetNameInfo(X509NameType.SimpleName, false);
+                // Use a different SNI for each connection to prevent TLS 1.3 renegotiation issue: https://github.com/dotnet/runtime/issues/47378
+                string serverName = TestHelper.GetTestSNIName(nameof(ServerAsyncSslHelper), clientSslProtocols, serverSslProtocols);
 
                 _log.WriteLine("Connected on {0} {1} ({2} {3})", clientStream.Socket.LocalEndPoint, clientStream.Socket.RemoteEndPoint, clientStream.Socket.Handle, serverStream.Socket.Handle);
                 _log.WriteLine("client SslStream#{0} server SslStream#{1}", sslClientStream.GetHashCode(),  sslServerStream.GetHashCode());
diff --git a/src/libraries/System.Net.Security/tests/FunctionalTests/SslStreamSystemDefaultsTest.cs b/src/libraries/System.Net.Security/tests/FunctionalTests/SslStreamSystemDefaultsTest.cs
index 0eebb02de11815..5380b4027a6f76 100644
--- a/src/libraries/System.Net.Security/tests/FunctionalTests/SslStreamSystemDefaultsTest.cs
+++ b/src/libraries/System.Net.Security/tests/FunctionalTests/SslStreamSystemDefaultsTest.cs
@@ -80,7 +80,7 @@ public async Task ClientAndServer_OneOrBothUseDefault_Ok(SslProtocols? clientPro
             using (X509Certificate2 clientCertificate = Configuration.Certificates.GetClientCertificate())
             {
                 // Use a different SNI for each connection to prevent TLS 1.3 renegotiation issue: https://github.com/dotnet/runtime/issues/47378
-                string serverHost = getTestSNIName();
+                string serverHost = TestHelper.GetTestSNIName(nameof(ClientAndServer_OneOrBothUseDefault_Ok), clientProtocols, serverProtocols);
                 var clientCertificates = new X509CertificateCollection() { clientCertificate };
 
                 await TestConfiguration.WhenAllOrAnyFailedWithTimeout(
@@ -100,16 +100,6 @@ await TestConfiguration.WhenAllOrAnyFailedWithTimeout(
                         _clientStream.SslProtocol + " " + _clientStream.HashAlgorithm);
                 }
             }
-
-            string getTestSNIName()
-            {
-                static string ProtocolToString(SslProtocols? protocol)
-                {
-                    return (protocol?.ToString() ?? "null").Replace(", ", "_");
-                }
-
-                return $"{nameof(ClientAndServer_OneOrBothUseDefault_Ok)}_{ProtocolToString(clientProtocols)}_{ProtocolToString(serverProtocols)}";
-            }
         }
 
         [ConditionalTheory(nameof(IsNotWindows7))]
diff --git a/src/libraries/System.Net.Security/tests/FunctionalTests/TestHelper.cs b/src/libraries/System.Net.Security/tests/FunctionalTests/TestHelper.cs
index ecdfeb47829a45..d9752147435b1f 100644
--- a/src/libraries/System.Net.Security/tests/FunctionalTests/TestHelper.cs
+++ b/src/libraries/System.Net.Security/tests/FunctionalTests/TestHelper.cs
@@ -2,8 +2,10 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.IO;
+using System.Linq;
 using System.Net.Sockets;
 using System.Net.Test.Common;
+using System.Security.Authentication;
 using System.Security.Cryptography;
 using System.Security.Cryptography.X509Certificates;
 using System.Security.Cryptography.X509Certificates.Tests.Common;
@@ -157,7 +159,7 @@ internal static (X509Certificate2 certificate, X509Certificate2Collection) Gener
                     intermedPub3.Dispose();
                     CertificateAuthority intermediateAuthority3 = new CertificateAuthority(intermedCert3, null, null, null);
 
-                    RSA  eeKey = (RSA)endEntity.PrivateKey;
+                    RSA eeKey = (RSA)endEntity.PrivateKey;
                     endEntity = intermediateAuthority3.CreateEndEntity(
                         $"CN=\"A SSL Test\", O=\"testName\"",
                         eeKey,
@@ -212,5 +214,18 @@ internal static async Task PingPong(SslStream client, SslStream server)
             Assert.Equal(s_pong, buffer);
             await t;
         }
+
+        internal static string GetTestSNIName(string testMethodName, params SslProtocols?[] protocols)
+        {
+            static string ProtocolToString(SslProtocols? protocol)
+            {
+                return (protocol?.ToString() ?? "null").Replace(", ", "-");
+            }
+
+            var args = string.Join(".", protocols.Select(p => ProtocolToString(p)));
+            var name = testMethodName.Length > 63 ? testMethodName.Substring(0, 63) : testMethodName;
+
+            return $"{name}.{args}";
+        }
     }
 }