diff --git a/.github/workflows/coding-standards.yml b/.github/workflows/coding-standards.yml
index 6de20675c0246..168863cdb6421 100644
--- a/.github/workflows/coding-standards.yml
+++ b/.github/workflows/coding-standards.yml
@@ -84,7 +84,7 @@ jobs:
         run: echo "::set-output name=date::$(/bin/date -u --date='last Mon' "+%F")"
 
       - name: Cache PHPCS scan cache
-        uses: actions/cache@136d96b4aee02b1f0de3ba493b1d47135042d9c0 # v3.0.1
+        uses: actions/cache@69d9d449aced6a2ede0bc19182fadc3a0a42d2b0 # v3.2.6
         with:
           path: .cache/phpcs.json
           key: ${{ runner.os }}-date-${{ steps.get-date.outputs.date }}-phpcs-cache-${{ hashFiles('**/composer.json', 'phpcs.xml.dist') }}
diff --git a/.github/workflows/php-compatibility.yml b/.github/workflows/php-compatibility.yml
index 79f5d97de58f6..1db95deb63696 100644
--- a/.github/workflows/php-compatibility.yml
+++ b/.github/workflows/php-compatibility.yml
@@ -78,7 +78,7 @@ jobs:
         run: echo "::set-output name=date::$(/bin/date -u --date='last Mon' "+%F")"
 
       - name: Cache PHP compatibility scan cache
-        uses: actions/cache@136d96b4aee02b1f0de3ba493b1d47135042d9c0 # v3.0.1
+        uses: actions/cache@69d9d449aced6a2ede0bc19182fadc3a0a42d2b0 # v3.2.6
         with:
           path: .cache/phpcompat.json
           key: ${{ runner.os }}-date-${{ steps.get-date.outputs.date }}-phpcompat-cache-${{ hashFiles('**/composer.json', 'phpcompat.xml.dist') }}
diff --git a/.github/workflows/phpunit-tests.yml b/.github/workflows/phpunit-tests.yml
index 578ebc6adf2b4..cc8bd5f190344 100644
--- a/.github/workflows/phpunit-tests.yml
+++ b/.github/workflows/phpunit-tests.yml
@@ -132,7 +132,7 @@ jobs:
         run: echo "::set-output name=dir::$(composer config cache-files-dir)"
 
       - name: Cache Composer dependencies
-        uses: actions/cache@136d96b4aee02b1f0de3ba493b1d47135042d9c0 # v3.0.1
+        uses: actions/cache@69d9d449aced6a2ede0bc19182fadc3a0a42d2b0 # v3.2.6
         env:
           cache-name: cache-composer-dependencies
         with:
diff --git a/.github/workflows/test-coverage.yml b/.github/workflows/test-coverage.yml
index f1b08567cd257..d1b9aae94ac54 100644
--- a/.github/workflows/test-coverage.yml
+++ b/.github/workflows/test-coverage.yml
@@ -96,7 +96,7 @@ jobs:
         run: echo "::set-output name=dir::$(composer config cache-files-dir)"
 
       - name: Cache Composer dependencies
-        uses: actions/cache@136d96b4aee02b1f0de3ba493b1d47135042d9c0 # v3.0.1
+        uses: actions/cache@69d9d449aced6a2ede0bc19182fadc3a0a42d2b0 # v3.2.6
         env:
           cache-name: cache-composer-dependencies
         with:
diff --git a/src/wp-admin/includes/network.php b/src/wp-admin/includes/network.php
index ae3e906fccd23..9fbd857e965e3 100644
--- a/src/wp-admin/includes/network.php
+++ b/src/wp-admin/includes/network.php
@@ -138,7 +138,10 @@ function network_step1( $errors = false ) {
 
 	$hostname  = get_clean_basedomain();
 	$has_ports = strstr( $hostname, ':' );
-	if ( ( false !== $has_ports && ! in_array( $has_ports, array( ':80', ':443' ), true ) ) ) {
+	/** This filter is documented in wp-includes/ms-settings.php */
+	$allowed_ports = apply_filters( 'allowed_multisite_ports', array( ':80', ':443' ) );
+
+	if ( ( false !== $has_ports && is_array( $allowed_ports ) && ! in_array( $has_ports, $allowed_ports, true ) ) ) {
 		echo '<div class="error"><p><strong>' . __( 'Error:' ) . '</strong> ' . __( 'You cannot install a network of sites with your server address.' ) . '</p></div>';
 		echo '<p>' . sprintf(
 			/* translators: %s: Port number. */
@@ -179,7 +182,7 @@ function network_step1( $errors = false ) {
 	}
 	?>
 	<p><?php _e( 'Welcome to the Network installation process!' ); ?></p>
-	<p><?php _e( 'Fill in the information below and you&#8217;ll be on your way to creating a network of WordPress sites. Configuration files will be created in the next step.' ); ?></p>
+	<p><?php _e( 'Fill in the information below and you&#8217;ll be on your way to creating a network of WordPress sites. We will create configuration files in the next step.' ); ?></p>
 	<?php
 
 	if ( isset( $_POST['subdomain_install'] ) ) {
@@ -271,7 +274,7 @@ function network_step1( $errors = false ) {
 		<?php
 		printf(
 			/* translators: 1: Site URL, 2: Host name, 3: www. */
-			__( 'You should consider changing your site domain to %1$s before enabling the network feature. It will still be possible to visit your site using the %3$s prefix with an address like %2$s but any links will not have the %3$s prefix.' ),
+			__( 'We recommend you change your site domain to %1$s before enabling the network feature. It will still be possible to visit your site using the %3$s prefix with an address like %2$s but any links will not have the %3$s prefix.' ),
 			'<code>' . substr( $hostname, 4 ) . '</code>',
 			'<code>' . $hostname . '</code>',
 			'<code>www</code>'
@@ -444,7 +447,7 @@ function network_step2( $errors = false ) {
 			echo '<strong>' . __( 'Caution:' ) . '</strong> ';
 			printf(
 				/* translators: 1: wp-config.php, 2: .htaccess */
-				__( 'You should back up your existing %1$s and %2$s files.' ),
+				__( 'We recommend you back up your existing %1$s and %2$s files.' ),
 				'<code>wp-config.php</code>',
 				'<code>.htaccess</code>'
 			);
@@ -452,7 +455,7 @@ function network_step2( $errors = false ) {
 			echo '<strong>' . __( 'Caution:' ) . '</strong> ';
 			printf(
 				/* translators: 1: wp-config.php, 2: web.config */
-				__( 'You should back up your existing %1$s and %2$s files.' ),
+				__( 'We recommend you back up your existing %1$s and %2$s files.' ),
 				'<code>wp-config.php</code>',
 				'<code>web.config</code>'
 			);
@@ -460,7 +463,7 @@ function network_step2( $errors = false ) {
 			echo '<strong>' . __( 'Caution:' ) . '</strong> ';
 			printf(
 				/* translators: %s: wp-config.php */
-				__( 'You should back up your existing %s file.' ),
+				__( 'We recommend you back up your existing %s file.' ),
 				'<code>wp-config.php</code>'
 			);
 		}
diff --git a/src/wp-includes/ms-settings.php b/src/wp-includes/ms-settings.php
index 6824895880f8b..1df500afa8968 100644
--- a/src/wp-includes/ms-settings.php
+++ b/src/wp-includes/ms-settings.php
@@ -54,15 +54,23 @@
 // have not been populated in the global scope through something like `sunrise.php`.
 if ( ! isset( $current_site ) || ! isset( $current_blog ) ) {
 
-	$domain = strtolower( stripslashes( $_SERVER['HTTP_HOST'] ) );
-	if ( ':80' === substr( $domain, -3 ) ) {
-		$domain               = substr( $domain, 0, -3 );
-		$_SERVER['HTTP_HOST'] = substr( $_SERVER['HTTP_HOST'], 0, -3 );
-	} elseif ( ':443' === substr( $domain, -4 ) ) {
-		$domain               = substr( $domain, 0, -4 );
-		$_SERVER['HTTP_HOST'] = substr( $_SERVER['HTTP_HOST'], 0, -4 );
+	/**
+	 * Filters allowed HTTP ports in Multisite.
+	 *
+	 * @since 6.0.0
+	 * @param array $allowed_ports The allowed ports. Default is [ ':80', ':443' ].
+	 */
+	$allowed_ports = apply_filters( 'allowed_multisite_ports', array( ':80', ':443' ) );
+
+	if ( is_array( $allowed_ports ) ) {
+		foreach ( $allowed_ports as $allowed_port ) {
+			$str_length = strlen( $allowed_port );
+			if ( str_ends_with( $domain, $allowed_port ) ) {
+				$domain               = substr( $domain, 0, - $str_length );
+				$_SERVER['HTTP_HOST'] = substr( $_SERVER['HTTP_HOST'], 0, - $str_length );
+			}
+		}
 	}
-
 	$path = stripslashes( $_SERVER['REQUEST_URI'] );
 	if ( is_admin() ) {
 		$path = preg_replace( '#(.*)/wp-admin/.*#', '$1/', $path );
diff --git a/src/wp-includes/ms-site.php b/src/wp-includes/ms-site.php
index cdce8ff03381a..ed94bc95d83c5 100644
--- a/src/wp-includes/ms-site.php
+++ b/src/wp-includes/ms-site.php
@@ -503,7 +503,17 @@ function wp_normalize_site_data( $data ) {
 	// Sanitize domain if passed.
 	if ( array_key_exists( 'domain', $data ) ) {
 		$data['domain'] = trim( $data['domain'] );
+		$has_ports      = strstr( $data['domain'], ':' );
+
+		// Remove ports.
+		$data['domain'] = preg_replace( '|:\d+$|', '', $data['domain'] );
 		$data['domain'] = preg_replace( '/\s+/', '', sanitize_user( $data['domain'], true ) );
+		/** This filter is documented in wp-includes/ms-settings.php */
+		$allowed_ports = apply_filters( 'allowed_multisite_ports', array( ':80', ':443' ) );
+		if ( ( false !== $has_ports && is_array( $allowed_ports ) && in_array( $has_ports, $allowed_ports, true ) ) ) {
+			$data['domain'] .= $has_ports;
+		}
+
 		if ( is_subdomain_install() ) {
 			$data['domain'] = str_replace( '@', '', $data['domain'] );
 		}
diff --git a/tests/phpunit/tests/multisite/site.php b/tests/phpunit/tests/multisite/site.php
index e2d4d78ddb98b..b25f54dbaee41 100644
--- a/tests/phpunit/tests/multisite/site.php
+++ b/tests/phpunit/tests/multisite/site.php
@@ -1603,6 +1603,12 @@ public function action_wp_validate_site_deletion_prevent_deletion( $errors ) {
 		 * @dataProvider data_wp_normalize_site_data
 		 */
 		public function test_wp_normalize_site_data( $data, $expected ) {
+			add_filter(
+				'allowed_multisite_ports',
+				function( $ports ) {
+					return array( ':80', ':443', ':8080' );
+				}
+			);
 			$result = wp_normalize_site_data( $data );
 
 			$this->assertSameSetsWithIndex( $expected, $result );
@@ -1674,6 +1680,30 @@ public function data_wp_normalize_site_data() {
 					),
 					array(),
 				),
+				array(
+					array(
+						'domain' => 'domainwithport.com:443',
+					),
+					array(
+						'domain' => 'domainwithport.com:443',
+					),
+				),
+				array(
+					array(
+						'domain' => 'anotherdomainwithport.com:80',
+					),
+					array(
+						'domain' => 'anotherdomainwithport.com:80',
+					),
+				),
+				array(
+					array(
+						'domain' => 'anotherwithport.com:8080',
+					),
+					array(
+						'domain' => 'anotherwithport.com:8080',
+					),
+				),
 			);
 		}