diff --git a/lib/connection_string.js b/lib/connection_string.js
index 622fc2c8c2..7608399230 100644
--- a/lib/connection_string.js
+++ b/lib/connection_string.js
@@ -720,14 +720,6 @@ function parseConnectionString(uri, options, callback) {
     return callback(new MongoParseError('directConnection option requires exactly one host'));
   }
 
-  // NOTE: this behavior will go away in v4.0, we will always auto discover there
-  if (
-    parsedOptions.directConnection == null &&
-    hosts.length === 1 &&
-    parsedOptions.replicaSet == null
-  ) {
-    parsedOptions.directConnection = true;
-  }
 
   const result = {
     hosts: hosts,
diff --git a/lib/sdam/server_selection.js b/lib/sdam/server_selection.js
index bfa33f07e9..d34387d687 100644
--- a/lib/sdam/server_selection.js
+++ b/lib/sdam/server_selection.js
@@ -187,6 +187,10 @@ function readPreferenceServerSelector(readPreference) {
       );
     }
 
+    if (topologyDescription.type === TopologyType.Unknown) {
+      return [];
+    }
+
     if (
       topologyDescription.type === TopologyType.Single ||
       topologyDescription.type === TopologyType.Sharded