diff --git a/akka-stream-tests/src/test/scala/akka/stream/io/TcpSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/io/TcpSpec.scala
index 00dad374f0..955ab1b60e 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/io/TcpSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/io/TcpSpec.scala
@@ -469,9 +469,11 @@ class TcpSpec extends StreamSpec("akka.stream.materializer.subscription-timeout.
       val resultFuture =
         Source(testInput).via(Tcp().outgoingConnection(serverAddress)).runFold(ByteString.empty)((acc, in) ⇒ acc ++ in)
 
+      binding.whenUnbound.value should be(None)
       resultFuture.futureValue should be(expectedOutput)
       binding.unbind().futureValue
       echoServerFinish.futureValue
+      binding.whenUnbound.futureValue should be(Done)
     }
 
     "work with a chain of echoes" in {
@@ -484,6 +486,7 @@ class TcpSpec extends StreamSpec("akka.stream.materializer.subscription-timeout.
 
       // make sure that the server has bound to the socket
       val binding = bindingFuture.futureValue
+      binding.whenUnbound.value should be(None)
 
       val echoConnection = Tcp().outgoingConnection(serverAddress)
 
@@ -501,6 +504,7 @@ class TcpSpec extends StreamSpec("akka.stream.materializer.subscription-timeout.
       resultFuture.futureValue should be(expectedOutput)
       binding.unbind().futureValue
       echoServerFinish.futureValue
+      binding.whenUnbound.futureValue should be(Done)
     }
 
     "bind and unbind correctly" in EventFilter[BindException](occurrences = 2).intercept {
diff --git a/akka-stream/src/main/mima-filters/2.5.6.backwards.excludes b/akka-stream/src/main/mima-filters/2.5.6.backwards.excludes
index 5d2732768e..2f1ec9b84b 100644
--- a/akka-stream/src/main/mima-filters/2.5.6.backwards.excludes
+++ b/akka-stream/src/main/mima-filters/2.5.6.backwards.excludes
@@ -33,4 +33,10 @@ ProblemFilters.exclude[IncompatibleMethTypeProblem]("akka.stream.impl.fusing.Gra
 ProblemFilters.exclude[DirectMissingMethodProblem]("akka.stream.impl.fusing.GraphInterpreterShell#AsyncInput.apply")
 ProblemFilters.exclude[IncompatibleResultTypeProblem]("akka.stream.impl.fusing.GraphInterpreterShell#AsyncInput.copy$default$4")
 ProblemFilters.exclude[DirectMissingMethodProblem]("akka.stream.impl.fusing.GraphInterpreterShell#AsyncInput.this")
-ProblemFilters.exclude[DirectMissingMethodProblem]("akka.stream.impl.fusing.GraphInterpreter.runAsyncInput")
\ No newline at end of file
+ProblemFilters.exclude[DirectMissingMethodProblem]("akka.stream.impl.fusing.GraphInterpreter.runAsyncInput")
+
+# 23798 observable unbind on stream Tcp server
+ProblemFilters.exclude[FinalClassProblem]("akka.stream.javadsl.Tcp$ServerBinding")
+ProblemFilters.exclude[DirectMissingMethodProblem]("akka.stream.scaladsl.Tcp#ServerBinding.copy")
+ProblemFilters.exclude[DirectMissingMethodProblem]("akka.stream.scaladsl.Tcp#ServerBinding.this")
+ProblemFilters.exclude[DirectMissingMethodProblem]("akka.stream.scaladsl.Tcp#ServerBinding.apply")
diff --git a/akka-stream/src/main/scala/akka/stream/impl/io/TcpStages.scala b/akka-stream/src/main/scala/akka/stream/impl/io/TcpStages.scala
index 8c06148b55..9e621f8da5 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/io/TcpStages.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/io/TcpStages.scala
@@ -7,7 +7,7 @@ import java.net.InetSocketAddress
 import java.util.concurrent.TimeoutException
 import java.util.concurrent.atomic.{ AtomicBoolean, AtomicLong }
 
-import akka.NotUsed
+import akka.{ Done, NotUsed }
 import akka.actor.{ ActorRef, Terminated }
 import akka.annotation.InternalApi
 import akka.dispatch.ExecutionContexts
@@ -76,7 +76,7 @@ import scala.concurrent.{ Future, Promise }
               // stopped.
               thisStage.tell(Unbind, thisStage)
               unbindPromise.future
-            }))
+            }, unbindPromise.future.map(_ ⇒ Done)(ExecutionContexts.sameThreadExecutionContext)))
           case f: CommandFailed ⇒
             val ex = new BindFailedException {
               // cannot modify the actual exception class for compatibility reasons
@@ -84,7 +84,7 @@ import scala.concurrent.{ Future, Promise }
             }
             f.cause.foreach(ex.initCause)
             bindingPromise.failure(ex)
-            unbindPromise.success(() ⇒ Future.successful(()))
+            unbindPromise.tryFailure(ex)
             failStage(ex)
           case c: Connected ⇒
             push(out, connectionFor(c, sender))
@@ -96,8 +96,10 @@ import scala.concurrent.{ Future, Promise }
             if (unbindStarted) {
               unbindCompleted()
             } else {
-              failStage(new IllegalStateException("IO Listener actor terminated unexpectedly for remote endpoint [" +
-                endpoint.getHostString + ":" + endpoint.getPort + "]"))
+              val ex = new IllegalStateException("IO Listener actor terminated unexpectedly for remote endpoint [" +
+                endpoint.getHostString + ":" + endpoint.getPort + "]")
+              unbindPromise.tryFailure(ex)
+              failStage(ex)
             }
         }
       }
@@ -144,6 +146,7 @@ import scala.concurrent.{ Future, Promise }
 
       private def unbindCompleted(): Unit = {
         stageActor.unwatch(listener)
+        unbindPromise.trySuccess(Done)
         if (connectionFlowsAwaitingInitialization.get() == 0) completeStage()
         else scheduleOnce(BindShutdownTimer, bindShutdownTimeout)
       }
@@ -154,7 +157,9 @@ import scala.concurrent.{ Future, Promise }
       }
 
       override def postStop(): Unit = {
-        unbindPromise.trySuccess(())
+        // a bit unexpected to succeed here rather than fail with abrupt stage termination
+        // but there was an existing test case covering this behavior
+        unbindPromise.trySuccess(Done)
         bindingPromise.tryFailure(new NoSuchElementException("Binding was unbound before it was completely finished"))
       }
     }
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Tcp.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Tcp.scala
index e6b13cf0ce..eec6b899a8 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Tcp.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Tcp.scala
@@ -5,9 +5,12 @@ package akka.stream.javadsl
 
 import java.lang.{ Iterable ⇒ JIterable }
 import java.util.Optional
-import akka.NotUsed
+
+import akka.{ Done, NotUsed }
+
 import scala.concurrent.duration._
 import java.net.InetSocketAddress
+
 import akka.actor.ActorSystem
 import akka.actor.ExtendedActorSystem
 import akka.actor.ExtensionId
@@ -17,16 +20,21 @@ import akka.stream.scaladsl
 import akka.util.ByteString
 import akka.japi.Util.immutableSeq
 import akka.io.Inet.SocketOption
+
 import scala.compat.java8.OptionConverters._
 import scala.compat.java8.FutureConverters._
 import java.util.concurrent.CompletionStage
 
+import akka.annotation.InternalApi
+
 object Tcp extends ExtensionId[Tcp] with ExtensionIdProvider {
 
   /**
    * Represents a prospective TCP server binding.
+   *
+   * Not indented for user construction
    */
-  class ServerBinding private[akka] (delegate: scaladsl.Tcp.ServerBinding) {
+  final class ServerBinding @InternalApi private[akka] (delegate: scaladsl.Tcp.ServerBinding) {
     /**
      * The local address of the endpoint bound by the materialization of the `connections` [[Source]].
      */
@@ -39,6 +47,11 @@ object Tcp extends ExtensionId[Tcp] with ExtensionIdProvider {
      * The produced [[java.util.concurrent.CompletionStage]] is fulfilled when the unbinding has been completed.
      */
     def unbind(): CompletionStage[Unit] = delegate.unbind().toJava
+
+    /**
+     * @return A completion stage that is completed when manually unbound, or failed if the server fails
+     */
+    def whenUnbound(): CompletionStage[Done] = delegate.whenUnbound.toJava
   }
 
   /**
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/Tcp.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/Tcp.scala
index c7770ac05a..68bd0a5ce2 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Tcp.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Tcp.scala
@@ -6,8 +6,9 @@ package akka.stream.scaladsl
 import java.net.InetSocketAddress
 import java.util.concurrent.TimeoutException
 
-import akka.NotUsed
+import akka.{ Done, NotUsed }
 import akka.actor._
+import akka.annotation.InternalApi
 import akka.io.Inet.SocketOption
 import akka.io.{ IO, Tcp ⇒ IoTcp }
 import akka.stream._
@@ -23,9 +24,18 @@ import scala.util.control.NoStackTrace
 object Tcp extends ExtensionId[Tcp] with ExtensionIdProvider {
 
   /**
-   * * Represents a successful TCP server binding.
+   * Represents a successful TCP server binding.
+   *
+   * Not indented for user construction
+   *
+   * @param localAddress The address the server was bound to
+   * @param unbindAction a function that will trigger unbind of the server
+   * @param whenUnbound A future that is completed when the server is unbound, or failed if the server binding fails
    */
-  final case class ServerBinding(localAddress: InetSocketAddress)(private val unbindAction: () ⇒ Future[Unit]) {
+  final case class ServerBinding @InternalApi private[akka] (localAddress: InetSocketAddress)(
+    private val unbindAction: () ⇒ Future[Unit],
+    val whenUnbound:          Future[Done]
+  ) {
     def unbind(): Future[Unit] = unbindAction()
   }