diff --git a/wrapper/src/main/java/software/amazon/jdbc/plugin/IamAuthConnectionPlugin.java b/wrapper/src/main/java/software/amazon/jdbc/plugin/IamAuthConnectionPlugin.java
index 8ca84b0b1..33fdf864d 100644
--- a/wrapper/src/main/java/software/amazon/jdbc/plugin/IamAuthConnectionPlugin.java
+++ b/wrapper/src/main/java/software/amazon/jdbc/plugin/IamAuthConnectionPlugin.java
@@ -107,20 +107,7 @@ private Connection connectInternal(String driverProtocol, HostSpec hostSpec, Pro
       host = IAM_HOST.getString(props);
     }
 
-    int port = hostSpec.getPort();
-    if (!hostSpec.isPortSpecified()) {
-      if (StringUtils.isNullOrEmpty(IAM_DEFAULT_PORT.getString(props))) {
-        port = this.pluginService.getDialect().getDefaultPort();
-      } else {
-        port = IAM_DEFAULT_PORT.getInteger(props);
-        if (port <= 0) {
-          throw new IllegalArgumentException(
-              Messages.get(
-                  "IamAuthConnectionPlugin.invalidPort",
-                  new Object[] {port}));
-        }
-      }
-    }
+    int port = getPort(props, hostSpec);
 
     final String iamRegion = IAM_REGION.getString(props);
     final Region region = StringUtils.isNullOrEmpty(iamRegion)
@@ -245,6 +232,26 @@ public static void clearCache() {
     tokenCache.clear();
   }
 
+  private int getPort(Properties props, HostSpec hostSpec) {
+    if (!StringUtils.isNullOrEmpty(IAM_DEFAULT_PORT.getString(props))) {
+      int defaultPort = IAM_DEFAULT_PORT.getInteger(props);
+      if (defaultPort > 0) {
+        return defaultPort;
+      } else {
+        LOGGER.finest(
+            () -> Messages.get(
+                "IamAuthConnectionPlugin.invalidPort",
+                new Object[] {defaultPort}));
+      }
+    }
+
+    if (hostSpec.isPortSpecified()) {
+      return hostSpec.getPort();
+    } else {
+      return this.pluginService.getDialect().getDefaultPort();
+    }
+  }
+
   private Region getRdsRegion(final String hostname) throws SQLException {
 
     // Get Region
diff --git a/wrapper/src/main/resources/messages.properties b/wrapper/src/main/resources/messages.properties
index 4a002248f..57bc397de 100644
--- a/wrapper/src/main/resources/messages.properties
+++ b/wrapper/src/main/resources/messages.properties
@@ -162,7 +162,7 @@ HostSelector.noHostsMatchingRole=No hosts were found matching the requested ''{0
 IamAuthConnectionPlugin.unsupportedHostname=Unsupported AWS hostname {0}. Amazon domain name in format *.AWS-Region.rds.amazonaws.com or *.rds.AWS-Region.amazonaws.com.cn is expected.
 IamAuthConnectionPlugin.useCachedIamToken=Use cached IAM token = ''{0}''
 IamAuthConnectionPlugin.generatedNewIamToken=Generated new IAM token = ''{0}''
-IamAuthConnectionPlugin.invalidPort=Port number: {0} is not valid. Port number should be greater than zero.
+IamAuthConnectionPlugin.invalidPort=Port number: {0} is not valid. Port number should be greater than zero. Falling back to default port.
 IamAuthConnectionPlugin.unhandledException=Unhandled exception: ''{0}''
 IamAuthConnectionPlugin.connectException=Error occurred while opening a connection: ''{0}''
 
diff --git a/wrapper/src/test/java/software/amazon/jdbc/plugin/IamAuthConnectionPluginTest.java b/wrapper/src/test/java/software/amazon/jdbc/plugin/IamAuthConnectionPluginTest.java
index 879d6dcc3..3cb62ce4e 100644
--- a/wrapper/src/test/java/software/amazon/jdbc/plugin/IamAuthConnectionPluginTest.java
+++ b/wrapper/src/test/java/software/amazon/jdbc/plugin/IamAuthConnectionPluginTest.java
@@ -113,15 +113,31 @@ public void testMySqlConnectValidTokenInCache() throws SQLException {
   }
 
   @Test
-  public void testPostgresConnectWithInvalidPort() {
-    props.setProperty("iamDefaultPort", "0");
-    PluginService mockPluginService = Mockito.mock(PluginService.class);
-    final IamAuthConnectionPlugin targetPlugin = new IamAuthConnectionPlugin(mockPluginService);
+  public void testPostgresConnectWithInvalidPortFallbacksToHostPort() throws SQLException {
+    final String invalidIamDefaultPort = "0";
+    props.setProperty(IamAuthConnectionPlugin.IAM_DEFAULT_PORT.name, invalidIamDefaultPort);
 
-    final IllegalArgumentException exception = assertThrows(IllegalArgumentException.class,
-        () -> targetPlugin.connect(PG_DRIVER_PROTOCOL, PG_HOST_SPEC, props, true, mockLambda));
+    final String cacheKeyWithNewPort = "us-east-2:pg.testdb.us-east-2.rds.amazonaws.com:"
+        + PG_HOST_SPEC_WITH_PORT.getPort() + ":postgresqlUser";
+    IamAuthConnectionPlugin.tokenCache.put(cacheKeyWithNewPort,
+        new IamAuthConnectionPlugin.TokenInfo(TEST_TOKEN, Instant.now().plusMillis(300000)));
 
-    assertEquals("Port number: 0 is not valid. Port number should be greater than zero.", exception.getMessage());
+    testTokenSetInProps(PG_DRIVER_PROTOCOL, PG_HOST_SPEC_WITH_PORT);
+  }
+
+  @Test
+  public void testPostgresConnectWithInvalidPortAndNoHostPortFallbacksToHostPort() throws SQLException {
+    final String invalidIamDefaultPort = "0";
+    props.setProperty(IamAuthConnectionPlugin.IAM_DEFAULT_PORT.name, invalidIamDefaultPort);
+
+    when(mockDialect.getDefaultPort()).thenReturn(DEFAULT_PG_PORT);
+
+    final String cacheKeyWithNewPort = "us-east-2:pg.testdb.us-east-2.rds.amazonaws.com:"
+        + DEFAULT_PG_PORT + ":postgresqlUser";
+    IamAuthConnectionPlugin.tokenCache.put(cacheKeyWithNewPort,
+        new IamAuthConnectionPlugin.TokenInfo(TEST_TOKEN, Instant.now().plusMillis(300000)));
+
+    testTokenSetInProps(PG_DRIVER_PROTOCOL, PG_HOST_SPEC);
   }
 
   @Test
@@ -150,6 +166,18 @@ public void testConnectWithSpecifiedPort() throws SQLException {
     testTokenSetInProps(PG_DRIVER_PROTOCOL, PG_HOST_SPEC_WITH_PORT);
   }
 
+  @Test
+  public void testConnectWithSpecifiedIamDefaultPort() throws SQLException {
+    final String iamDefaultPort = "9999";
+    props.setProperty(IamAuthConnectionPlugin.IAM_DEFAULT_PORT.name, iamDefaultPort);
+    final String cacheKeyWithNewPort = "us-east-2:pg.testdb.us-east-2.rds.amazonaws.com:"
+        + iamDefaultPort + ":postgresqlUser";
+    IamAuthConnectionPlugin.tokenCache.put(cacheKeyWithNewPort,
+        new IamAuthConnectionPlugin.TokenInfo(TEST_TOKEN, Instant.now().plusMillis(300000)));
+
+    testTokenSetInProps(PG_DRIVER_PROTOCOL, PG_HOST_SPEC_WITH_PORT);
+  }
+
   @Test
   public void testConnectWithSpecifiedRegion() throws SQLException {
     final String cacheKeyWithNewRegion =