diff --git a/android/Gutenberg/src/main/java/org/wordpress/gutenberg/GutenbergView.kt b/android/Gutenberg/src/main/java/org/wordpress/gutenberg/GutenbergView.kt
index d269ddb5e..22168f5b2 100644
--- a/android/Gutenberg/src/main/java/org/wordpress/gutenberg/GutenbergView.kt
+++ b/android/Gutenberg/src/main/java/org/wordpress/gutenberg/GutenbergView.kt
@@ -518,11 +518,8 @@ class GutenbergView : FrameLayout {
                 }
 
                 // Allow local development server if configured
-                if (BuildConfig.GUTENBERG_EDITOR_URL.isNotEmpty()) {
-                    val editorUrl = Uri.parse(BuildConfig.GUTENBERG_EDITOR_URL)
-                    if (url.host == editorUrl.host) {
-                        return false
-                    }
+                if (isDevServerUrl(url, BuildConfig.GUTENBERG_EDITOR_URL)) {
+                    return false
                 }
 
                 // For all other URLs, open in external browser
@@ -1400,6 +1397,19 @@ class GutenbergView : FrameLayout {
             return if (uri.port != -1 && uri.port != defaultPort) "$host:${uri.port}" else host
         }
 
+        /**
+         * Whether [url] is on the local development server at [editorUrl]. Compares
+         * host and port so another port on the same host, such as a local WordPress
+         * site beside the dev server, isn't treated as the dev server.
+         *
+         * Returns false when [editorUrl] has no host (unset or missing a scheme), so
+         * host-less URLs like `mailto:` never match it.
+         */
+        internal fun isDevServerUrl(url: Uri, editorUrl: String): Boolean {
+            val devServerAuthority = originAuthority(editorUrl) ?: return false
+            return url.authority == devServerAuthority
+        }
+
         private const val ASSET_LOADING_TIMEOUT_MS = 5000L
 
         /**
diff --git a/android/Gutenberg/src/test/java/org/wordpress/gutenberg/GutenbergViewTest.kt b/android/Gutenberg/src/test/java/org/wordpress/gutenberg/GutenbergViewTest.kt
index f4c283653..07fe1668c 100644
--- a/android/Gutenberg/src/test/java/org/wordpress/gutenberg/GutenbergViewTest.kt
+++ b/android/Gutenberg/src/test/java/org/wordpress/gutenberg/GutenbergViewTest.kt
@@ -292,6 +292,48 @@ class GutenbergViewTest {
         assertEquals(null, GutenbergView.originAuthority("not a url"))
     }
 
+    // ===== isDevServerUrl =====
+
+    @Test
+    fun `isDevServerUrl matches the dev server's host and port`() {
+        assertTrue(
+            GutenbergView.isDevServerUrl(
+                Uri.parse("http://10.0.2.2:5173/src/index.html"),
+                "http://10.0.2.2:5173/"
+            )
+        )
+    }
+
+    @Test
+    fun `isDevServerUrl rejects another port on the dev server's host`() {
+        assertFalse(
+            GutenbergView.isDevServerUrl(Uri.parse("http://10.0.2.2:8888/"), "http://10.0.2.2:5173/")
+        )
+        assertFalse(
+            GutenbergView.isDevServerUrl(Uri.parse("http://10.0.2.2/"), "http://10.0.2.2:5173/")
+        )
+    }
+
+    @Test
+    fun `isDevServerUrl matches a dev server URL written with its default port`() {
+        // Chromium drops a default port before the URL reaches the WebViewClient.
+        assertTrue(
+            GutenbergView.isDevServerUrl(Uri.parse("http://localhost/"), "http://localhost:80/")
+        )
+    }
+
+    @Test
+    fun `isDevServerUrl rejects every URL when no dev server is configured`() {
+        assertFalse(GutenbergView.isDevServerUrl(Uri.parse("http://localhost:5173/"), ""))
+    }
+
+    @Test
+    fun `isDevServerUrl rejects host-less URLs when the dev server URL has no host`() {
+        // Without a scheme, the dev server URL has no authority, and neither do these.
+        assertFalse(GutenbergView.isDevServerUrl(Uri.parse("mailto:a@example.com"), "10.0.2.2:5173"))
+        assertFalse(GutenbergView.isDevServerUrl(Uri.parse("tel:5551234"), "10.0.2.2:5173"))
+    }
+
     // ===== REST API navigation =====
 
     @Test
diff --git a/android/build.gradle.kts b/android/build.gradle.kts
index 454b87067..c693855b1 100644
--- a/android/build.gradle.kts
+++ b/android/build.gradle.kts
@@ -6,7 +6,7 @@ if (localPropertiesFile.exists()) {
 }
 
 ext {
-    set("gutenbergEditorUrl", localProperties.getProperty("GUTENBERG_EDITOR_URL") ?: "")
+    set("gutenbergEditorUrl", localProperties.getProperty("GUTENBERG_EDITOR_URL")?.trim() ?: "")
 }
 
 plugins {