diff --git a/packages/dev-middleware/src/__tests__/InspectorProxyCdpRewritingHacks-test.js b/packages/dev-middleware/src/__tests__/InspectorProxyCdpRewritingHacks-test.js
index b2d83c053d3..2f5eab91061 100644
--- a/packages/dev-middleware/src/__tests__/InspectorProxyCdpRewritingHacks-test.js
+++ b/packages/dev-middleware/src/__tests__/InspectorProxyCdpRewritingHacks-test.js
@@ -192,7 +192,7 @@ describe.each(['HTTP', 'HTTPS'])(
       }
     });
 
-    describe.each(['10.0.2.2', '10.0.3.2'])(
+    describe.each(['10.0.2.2', '10.0.3.2', '127.0.0.1'])(
       '%s aliasing to and from localhost',
       sourceHost => {
         test('in source map fetching during Debugger.scriptParsed', async () => {
diff --git a/packages/dev-middleware/src/inspector-proxy/Device.js b/packages/dev-middleware/src/inspector-proxy/Device.js
index b9481dac910..1ecfd66f653 100644
--- a/packages/dev-middleware/src/inspector-proxy/Device.js
+++ b/packages/dev-middleware/src/inspector-proxy/Device.js
@@ -37,8 +37,21 @@ const debug = require('debug')('Metro:InspectorProxy');
 
 const PAGES_POLLING_INTERVAL = 1000;
 
-// Android's stock emulator and other emulators such as genymotion use a standard localhost alias.
-const EMULATOR_LOCALHOST_ADDRESSES: Array<string> = ['10.0.2.2', '10.0.3.2'];
+// Replace hosts appearing in the `url` and `sourceMapURL` fields of
+// `Debugger.scriptParsed`, and back again in messages from the debugger,
+// to account for device/debugger/proxy running on different networks.
+const REWRITE_HOSTS_TO_LOCALHOST: Array<string> = [
+  // A device may retrieve a bundle through 127.0.0.1 via a (SSH) tunnel, but
+  // the (remote) Metro server may be on a host without an IPv4 loopback, so
+  // 127.0.0.1 may not be addressible locally for (e.g., for source map
+  // fetching). Replacing with the more general 'localhost' should always be
+  // safe while also more compatible with IPv6-only setups.
+  '127.0.0.1',
+  // Android's stock emulator and other emulators such as genymotion use a
+  // standard localhost alias.
+  '10.0.2.2',
+  '10.0.3.2',
+];
 
 // Prefix for script URLs that are alphanumeric IDs. See comment in #processMessageFromDeviceLegacy method for
 // more details.
@@ -621,15 +634,14 @@ export default class Device {
     ) {
       const params = payload.params;
       if ('sourceMapURL' in params) {
-        for (let i = 0; i < EMULATOR_LOCALHOST_ADDRESSES.length; ++i) {
-          const address = EMULATOR_LOCALHOST_ADDRESSES[i];
-          if (params.sourceMapURL.includes(address)) {
+        for (const hostToRewrite of REWRITE_HOSTS_TO_LOCALHOST) {
+          if (params.sourceMapURL.includes(hostToRewrite)) {
             // $FlowFixMe[cannot-write]
             payload.params.sourceMapURL = params.sourceMapURL.replace(
-              address,
+              hostToRewrite,
               'localhost',
             );
-            debuggerInfo.originalSourceURLAddress = address;
+            debuggerInfo.originalSourceURLAddress = hostToRewrite;
           }
         }
 
@@ -654,12 +666,11 @@ export default class Device {
         }
       }
       if ('url' in params) {
-        for (let i = 0; i < EMULATOR_LOCALHOST_ADDRESSES.length; ++i) {
-          const address = EMULATOR_LOCALHOST_ADDRESSES[i];
-          if (params.url.indexOf(address) >= 0) {
+        for (const hostToRewrite of REWRITE_HOSTS_TO_LOCALHOST) {
+          if (params.url.includes(hostToRewrite)) {
             // $FlowFixMe[cannot-write]
-            payload.params.url = params.url.replace(address, 'localhost');
-            debuggerInfo.originalSourceURLAddress = address;
+            payload.params.url = params.url.replace(hostToRewrite, 'localhost');
+            debuggerInfo.originalSourceURLAddress = hostToRewrite;
           }
         }