diff --git a/okhttp-testing-support/src/main/kotlin/okhttp3/ConnectionEvent.kt b/okhttp-testing-support/src/main/kotlin/okhttp3/ConnectionEvent.kt
index 2dded160c..d77e31d15 100644
--- a/okhttp-testing-support/src/main/kotlin/okhttp3/ConnectionEvent.kt
+++ b/okhttp-testing-support/src/main/kotlin/okhttp3/ConnectionEvent.kt
@@ -13,6 +13,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+@file:Suppress(
+  "CANNOT_OVERRIDE_INVISIBLE_MEMBER",
+  "INVISIBLE_MEMBER",
+  "INVISIBLE_REFERENCE",
+)
 
 package okhttp3
 
diff --git a/okhttp-testing-support/src/main/kotlin/okhttp3/OkHttpClientTestRule.kt b/okhttp-testing-support/src/main/kotlin/okhttp3/OkHttpClientTestRule.kt
index 82abccdc5..00cc62985 100644
--- a/okhttp-testing-support/src/main/kotlin/okhttp3/OkHttpClientTestRule.kt
+++ b/okhttp-testing-support/src/main/kotlin/okhttp3/OkHttpClientTestRule.kt
@@ -60,7 +60,7 @@ class OkHttpClientTestRule :
   private lateinit var testName: String
   private var defaultUncaughtExceptionHandler: Thread.UncaughtExceptionHandler? = null
   private var taskQueuesWereIdle: Boolean = false
-  val connectionListener = RecordingConnectionListener()
+  private val connectionListener = RecordingConnectionListener()
 
   var logger: Logger? = null
 
diff --git a/okhttp-testing-support/src/main/kotlin/okhttp3/RecordingConnectionListener.kt b/okhttp-testing-support/src/main/kotlin/okhttp3/RecordingConnectionListener.kt
index 4313db231..3f5ce36c3 100644
--- a/okhttp-testing-support/src/main/kotlin/okhttp3/RecordingConnectionListener.kt
+++ b/okhttp-testing-support/src/main/kotlin/okhttp3/RecordingConnectionListener.kt
@@ -13,6 +13,12 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+@file:Suppress(
+  "CANNOT_OVERRIDE_INVISIBLE_MEMBER",
+  "INVISIBLE_MEMBER",
+  "INVISIBLE_REFERENCE",
+)
+
 package okhttp3
 
 import assertk.assertThat
@@ -24,11 +30,12 @@ import java.util.Deque
 import java.util.concurrent.ConcurrentLinkedDeque
 import java.util.concurrent.TimeUnit
 import okhttp3.ConnectionEvent.NoNewExchanges
+import okhttp3.internal.connection.ConnectionListener
 import okhttp3.internal.connection.RealConnection
 import okio.IOException
 import org.junit.jupiter.api.Assertions
 
-open class RecordingConnectionListener(
+internal open class RecordingConnectionListener(
   /**
    * An override to ignore the normal order that is enforced.
    * EventListeners added by Interceptors will not see all events.
diff --git a/okhttp-testing-support/src/main/kotlin/okhttp3/TestValueFactory.kt b/okhttp-testing-support/src/main/kotlin/okhttp3/TestValueFactory.kt
index a484d479a..6d2e4c9e1 100644
--- a/okhttp-testing-support/src/main/kotlin/okhttp3/TestValueFactory.kt
+++ b/okhttp-testing-support/src/main/kotlin/okhttp3/TestValueFactory.kt
@@ -36,6 +36,7 @@ import okhttp3.internal.concurrent.TaskFaker
 import okhttp3.internal.concurrent.TaskRunner
 import okhttp3.internal.concurrent.withLock
 import okhttp3.internal.connection.CallConnectionUser
+import okhttp3.internal.connection.ConnectionListener
 import okhttp3.internal.connection.FastFallbackExchangeFinder
 import okhttp3.internal.connection.RealCall
 import okhttp3.internal.connection.RealConnection
diff --git a/okhttp-testing-support/src/main/kotlin/okhttp3/internal/http2/Http2FlowControlConnectionListener.kt b/okhttp-testing-support/src/main/kotlin/okhttp3/internal/http2/Http2FlowControlConnectionListener.kt
deleted file mode 100644
index e60a3e67a..000000000
--- a/okhttp-testing-support/src/main/kotlin/okhttp3/internal/http2/Http2FlowControlConnectionListener.kt
+++ /dev/null
@@ -1,40 +0,0 @@
-/*
- * Copyright (C) 2023 Block, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package okhttp3.internal.http2
-
-import okhttp3.ConnectionListener
-import okhttp3.internal.http2.flowcontrol.WindowCounter
-
-/**
- * ConnectionListener that outputs CSV for flow control of client receiving streams.
- */
-class Http2FlowControlConnectionListener :
-  ConnectionListener(),
-  FlowControlListener {
-  val start = System.currentTimeMillis()
-
-  override fun receivingStreamWindowChanged(
-    streamId: Int,
-    windowCounter: WindowCounter,
-    bufferSize: Long,
-  ) {
-    println("${System.currentTimeMillis() - start},$streamId,${windowCounter.unacknowledged},$bufferSize")
-  }
-
-  override fun receivingConnectionWindowChanged(windowCounter: WindowCounter) {
-    println("${System.currentTimeMillis() - start},0,${windowCounter.unacknowledged},")
-  }
-}
diff --git a/okhttp/api/android/okhttp.api b/okhttp/api/android/okhttp.api
index 355bb5d27..28913fee9 100644
--- a/okhttp/api/android/okhttp.api
+++ b/okhttp/api/android/okhttp.api
@@ -333,27 +333,9 @@ public abstract interface class okhttp3/Connection {
 	public abstract fun socket ()Ljava/net/Socket;
 }
 
-public abstract class okhttp3/ConnectionListener {
-	public static final field Companion Lokhttp3/ConnectionListener$Companion;
-	public fun <init> ()V
-	public fun connectEnd (Lokhttp3/Connection;Lokhttp3/Route;Lokhttp3/Call;)V
-	public fun connectFailed (Lokhttp3/Route;Lokhttp3/Call;Ljava/io/IOException;)V
-	public fun connectStart (Lokhttp3/Route;Lokhttp3/Call;)V
-	public fun connectionAcquired (Lokhttp3/Connection;Lokhttp3/Call;)V
-	public fun connectionClosed (Lokhttp3/Connection;)V
-	public fun connectionReleased (Lokhttp3/Connection;Lokhttp3/Call;)V
-	public fun noNewExchanges (Lokhttp3/Connection;)V
-}
-
-public final class okhttp3/ConnectionListener$Companion {
-	public final fun getNONE ()Lokhttp3/ConnectionListener;
-}
-
 public final class okhttp3/ConnectionPool {
 	public fun <init> ()V
 	public fun <init> (IJLjava/util/concurrent/TimeUnit;)V
-	public fun <init> (IJLjava/util/concurrent/TimeUnit;Lokhttp3/ConnectionListener;)V
-	public synthetic fun <init> (IJLjava/util/concurrent/TimeUnit;Lokhttp3/ConnectionListener;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public final fun connectionCount ()I
 	public final fun evictAll ()V
 	public final fun idleConnectionCount ()I
diff --git a/okhttp/api/jvm/okhttp.api b/okhttp/api/jvm/okhttp.api
index 355bb5d27..28913fee9 100644
--- a/okhttp/api/jvm/okhttp.api
+++ b/okhttp/api/jvm/okhttp.api
@@ -333,27 +333,9 @@ public abstract interface class okhttp3/Connection {
 	public abstract fun socket ()Ljava/net/Socket;
 }
 
-public abstract class okhttp3/ConnectionListener {
-	public static final field Companion Lokhttp3/ConnectionListener$Companion;
-	public fun <init> ()V
-	public fun connectEnd (Lokhttp3/Connection;Lokhttp3/Route;Lokhttp3/Call;)V
-	public fun connectFailed (Lokhttp3/Route;Lokhttp3/Call;Ljava/io/IOException;)V
-	public fun connectStart (Lokhttp3/Route;Lokhttp3/Call;)V
-	public fun connectionAcquired (Lokhttp3/Connection;Lokhttp3/Call;)V
-	public fun connectionClosed (Lokhttp3/Connection;)V
-	public fun connectionReleased (Lokhttp3/Connection;Lokhttp3/Call;)V
-	public fun noNewExchanges (Lokhttp3/Connection;)V
-}
-
-public final class okhttp3/ConnectionListener$Companion {
-	public final fun getNONE ()Lokhttp3/ConnectionListener;
-}
-
 public final class okhttp3/ConnectionPool {
 	public fun <init> ()V
 	public fun <init> (IJLjava/util/concurrent/TimeUnit;)V
-	public fun <init> (IJLjava/util/concurrent/TimeUnit;Lokhttp3/ConnectionListener;)V
-	public synthetic fun <init> (IJLjava/util/concurrent/TimeUnit;Lokhttp3/ConnectionListener;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public final fun connectionCount ()I
 	public final fun evictAll ()V
 	public final fun idleConnectionCount ()I
diff --git a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/ConnectionPool.kt b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/ConnectionPool.kt
index 34af096c8..f787f8632 100644
--- a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/ConnectionPool.kt
+++ b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/ConnectionPool.kt
@@ -18,6 +18,7 @@ package okhttp3
 
 import java.util.concurrent.TimeUnit
 import okhttp3.internal.concurrent.TaskRunner
+import okhttp3.internal.connection.ConnectionListener
 import okhttp3.internal.connection.FastFallbackExchangeFinder
 import okhttp3.internal.connection.ForceConnectRoutePlanner
 import okhttp3.internal.connection.RealConnectionPool
@@ -82,9 +83,8 @@ class ConnectionPool internal constructor(
     ),
   )
 
-  // Public API
-  @ExperimentalOkHttpApi
-  constructor(
+  // Internal until we promote ConnectionListener to be a public API.
+  internal constructor(
     maxIdleConnections: Int = 5,
     keepAliveDuration: Long = 5,
     timeUnit: TimeUnit = TimeUnit.MINUTES,
diff --git a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/CallConnectionUser.kt b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/CallConnectionUser.kt
index 25de3b72a..5f2c7a315 100644
--- a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/CallConnectionUser.kt
+++ b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/CallConnectionUser.kt
@@ -20,7 +20,6 @@ import java.net.InetAddress
 import java.net.Proxy
 import java.net.Socket
 import okhttp3.Connection
-import okhttp3.ConnectionListener
 import okhttp3.EventListener
 import okhttp3.Handshake
 import okhttp3.HttpUrl
diff --git a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/ConnectionListener.kt b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/ConnectionListener.kt
similarity index 93%
rename from okhttp/src/commonJvmAndroid/kotlin/okhttp3/ConnectionListener.kt
rename to okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/ConnectionListener.kt
index 458e5ac4e..015782059 100644
--- a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/ConnectionListener.kt
+++ b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/ConnectionListener.kt
@@ -13,8 +13,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package okhttp3
+package okhttp3.internal.connection
 
+import okhttp3.Call
+import okhttp3.Connection
+import okhttp3.Route
 import okio.IOException
 
 /**
@@ -24,8 +27,7 @@ import okio.IOException
  * attempt to mutate the event parameters, or be reentrant back into the client.
  * Any IO - writing to files or network should be done asynchronously.
  */
-@ExperimentalOkHttpApi
-abstract class ConnectionListener {
+internal abstract class ConnectionListener {
   /**
    * Invoked as soon as a call causes a connection to be started.
    */
@@ -78,7 +80,6 @@ abstract class ConnectionListener {
    */
   open fun noNewExchanges(connection: Connection) {}
 
-  @ExperimentalOkHttpApi
   companion object {
     val NONE: ConnectionListener = object : ConnectionListener() {}
   }
diff --git a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/RealConnection.kt b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/RealConnection.kt
index ca3d388de..33d60d015 100644
--- a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/RealConnection.kt
+++ b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/RealConnection.kt
@@ -27,7 +27,6 @@ import javax.net.ssl.SSLPeerUnverifiedException
 import javax.net.ssl.SSLSocket
 import okhttp3.Address
 import okhttp3.Connection
-import okhttp3.ConnectionListener
 import okhttp3.Handshake
 import okhttp3.HttpUrl
 import okhttp3.OkHttpClient
@@ -67,7 +66,7 @@ import okio.buffer
  * Connections are shared in a connection pool. Accesses to the connection's state must be guarded
  * by holding a lock on the connection.
  */
-class RealConnection(
+class RealConnection internal constructor(
   val taskRunner: TaskRunner,
   val connectionPool: RealConnectionPool,
   override val route: Route,
diff --git a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/RealConnectionPool.kt b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/RealConnectionPool.kt
index 9207d6c15..867dea821 100644
--- a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/RealConnectionPool.kt
+++ b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/connection/RealConnectionPool.kt
@@ -22,7 +22,6 @@ import java.util.concurrent.ThreadLocalRandom
 import java.util.concurrent.TimeUnit
 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater
 import okhttp3.Address
-import okhttp3.ConnectionListener
 import okhttp3.ConnectionPool
 import okhttp3.Route
 import okhttp3.internal.closeQuietly
@@ -36,7 +35,7 @@ import okhttp3.internal.okHttpName
 import okhttp3.internal.platform.Platform
 import okio.IOException
 
-class RealConnectionPool(
+class RealConnectionPool internal constructor(
   private val taskRunner: TaskRunner,
   /**
    * The maximum number of idle connections across all addresses.
diff --git a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/internal.kt b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/internal.kt
index 1101e8fe0..5a87df07f 100644
--- a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/internal.kt
+++ b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/internal.kt
@@ -24,7 +24,6 @@ import java.nio.charset.Charset
 import javax.net.ssl.SSLSocket
 import okhttp3.Cache
 import okhttp3.CipherSuite
-import okhttp3.ConnectionListener
 import okhttp3.ConnectionPool
 import okhttp3.ConnectionSpec
 import okhttp3.Cookie
@@ -36,6 +35,7 @@ import okhttp3.OkHttpClient
 import okhttp3.Request
 import okhttp3.Response
 import okhttp3.internal.concurrent.TaskRunner
+import okhttp3.internal.connection.ConnectionListener
 import okhttp3.internal.connection.RealConnection
 
 internal fun parseCookie(
diff --git a/okhttp/src/jvmTest/kotlin/okhttp3/ConnectionListenerTest.kt b/okhttp/src/jvmTest/kotlin/okhttp3/ConnectionListenerTest.kt
index cc806f745..6ba4f19d0 100644
--- a/okhttp/src/jvmTest/kotlin/okhttp3/ConnectionListenerTest.kt
+++ b/okhttp/src/jvmTest/kotlin/okhttp3/ConnectionListenerTest.kt
@@ -13,6 +13,12 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+@file:Suppress(
+  "CANNOT_OVERRIDE_INVISIBLE_MEMBER",
+  "INVISIBLE_MEMBER",
+  "INVISIBLE_REFERENCE",
+)
+
 package okhttp3
 
 import assertk.assertThat
diff --git a/okhttp/src/jvmTest/kotlin/okhttp3/internal/connection/RouteSelectorTest.kt b/okhttp/src/jvmTest/kotlin/okhttp3/internal/connection/RouteSelectorTest.kt
index c16faaa3e..d61136b64 100644
--- a/okhttp/src/jvmTest/kotlin/okhttp3/internal/connection/RouteSelectorTest.kt
+++ b/okhttp/src/jvmTest/kotlin/okhttp3/internal/connection/RouteSelectorTest.kt
@@ -31,7 +31,6 @@ import java.net.URI
 import java.net.UnknownHostException
 import kotlin.test.assertFailsWith
 import okhttp3.Address
-import okhttp3.ConnectionListener
 import okhttp3.FakeDns
 import okhttp3.OkHttpClientTestRule
 import okhttp3.Request