diff --git a/driver-core/src/main/com/mongodb/internal/connection/DefaultSdamServerDescriptionManager.java b/driver-core/src/main/com/mongodb/internal/connection/DefaultSdamServerDescriptionManager.java
index af4acd8c03..e49ce50911 100644
--- a/driver-core/src/main/com/mongodb/internal/connection/DefaultSdamServerDescriptionManager.java
+++ b/driver-core/src/main/com/mongodb/internal/connection/DefaultSdamServerDescriptionManager.java
@@ -23,6 +23,8 @@
 import com.mongodb.connection.ServerType;
 import com.mongodb.event.ServerDescriptionChangedEvent;
 import com.mongodb.event.ServerListener;
+import com.mongodb.internal.diagnostics.logging.Logger;
+import com.mongodb.internal.diagnostics.logging.Loggers;
 
 import static com.mongodb.assertions.Assertions.assertFalse;
 import static com.mongodb.assertions.Assertions.assertNotNull;
@@ -30,9 +32,11 @@
 import static com.mongodb.connection.ServerType.UNKNOWN;
 import static com.mongodb.internal.connection.EventHelper.wouldDescriptionsGenerateEquivalentEvents;
 import static com.mongodb.internal.connection.ServerDescriptionHelper.unknownConnectingServerDescription;
+import static java.lang.String.format;
 
 @ThreadSafe
 final class DefaultSdamServerDescriptionManager implements SdamServerDescriptionManager {
+    private static final Logger LOGGER = Loggers.getLogger("connection");
     private final Cluster cluster;
     private final ServerId serverId;
     private final ServerListener serverListener;
@@ -135,6 +139,15 @@ private void handleException(final SdamIssue sdamIssue, final boolean beforeHand
                 connectionPool.invalidate(sdamIssue.exception().orElse(null));
             }
             serverMonitor.connect();
+        } else if (beforeHandshake
+                && (sdamIssue.relatedToNetworkNotTimeout() || sdamIssue.relatedToNetworkTimeout())) {
+            // clients MUST NOT clear the connection pool and MUST NOT mark the server Unknown when a connection establishment
+            // fails with network errors or timeouts
+            // TODO if we can detect reliably TLS handshake error (ex revoked certificate) we may choose to clear the pool and mark the
+            //  server unknown
+            LOGGER.info(format("Connection pool is not cleared and server is not marked Unknown since we encountered a timeout or network"
+                    + " error before the handshake: %s", sdamIssue.exception().orElse(null)));
+            serverMonitor.cancelCurrentCheck();
         } else if (sdamIssue.relatedToNetworkNotTimeout()
                 || (beforeHandshake && (sdamIssue.relatedToNetworkTimeout() || sdamIssue.relatedToAuth()))) {
             updateDescription(sdamIssue.serverDescription());
diff --git a/driver-core/src/test/unit/com/mongodb/internal/connection/DefaultServerSpecification.groovy b/driver-core/src/test/unit/com/mongodb/internal/connection/DefaultServerSpecification.groovy
index 3910da575f..cb6fd59e2b 100644
--- a/driver-core/src/test/unit/com/mongodb/internal/connection/DefaultServerSpecification.groovy
+++ b/driver-core/src/test/unit/com/mongodb/internal/connection/DefaultServerSpecification.groovy
@@ -234,7 +234,7 @@ class DefaultServerSpecification extends Specification {
         ]
     }
 
-    def 'failed open should invalidate the server'() {
+    def 'timeout and network error should not invalidate the pool'() {
         given:
         def connectionPool = Mock(ConnectionPool)
         connectionPool.get(_) >> { throw exceptionToThrow }
@@ -247,7 +247,7 @@ class DefaultServerSpecification extends Specification {
         then:
         def e = thrown(MongoException)
         e.is(exceptionToThrow)
-        1 * connectionPool.invalidate(exceptionToThrow)
+        0 * connectionPool.invalidate(exceptionToThrow)
         1 * serverMonitor.cancelCurrentCheck()
 
         where: