diff --git a/src/up.cmd.js b/src/up.cmd.js
index dab197a2a..41710b6af 100644
--- a/src/up.cmd.js
+++ b/src/up.cmd.js
@@ -100,11 +100,39 @@ export default class UpCommand extends AbstractServerCommand {
   }
 
   async verifyUrl(gitUrl, inref) {
+    // check if the site is on helix5
+    // https://admin.hlx.page/sidekick/adobe/www-aem-live/main/config.json
+    // {
+    //   "host": "aem.live",
+    //     "liveHost": "main--www-aem-live--adobe.aem.live",
+    //       "plugins": [
+    //         {
+    //           "id": "doc",
+    //           "title": "Documentation",
+    //           "url": "https://www.aem.live/docs/"
+    //         }
+    //       ],
+    //         "previewHost": "main--www-aem-live--adobe.aem.page",
+    //           "project": "Helix Website (AEM Live)",
+    //             "testProperty": "header";
+    // }
+    const configUrl = `https://admin.hlx.page/sidekick/${gitUrl.repo}/${gitUrl.owner}/${inref}/config.json`;
+    const configResp = await getFetch()(configUrl);
+    let previewHostBase = 'hlx.page';
+    if (configResp.ok) {
+      // this is best effort for now
+      const config = await configResp.json();
+      const { previewHost } = config;
+      if (previewHost && previewHost.endsWith('.aem.page')) {
+        previewHostBase = 'aem.page';
+      }
+    }
+
     let ref = inref;
 
     // replace `/` by `-` in ref.
     ref = ref.replace(/\//g, '-');
-    this._url = `https://${ref}--${gitUrl.repo}--${gitUrl.owner}.hlx.page`;
+    this._url = `https://${ref}--${gitUrl.repo}--${gitUrl.owner}.${previewHostBase}`;
     // check length limit
     if (this._url.split('.')
       .map((part) => part.replace(/^https:\/\//, ''))
@@ -125,7 +153,7 @@ export default class UpCommand extends AbstractServerCommand {
         this.log.warn(chalk`Unable to verify {yellow main} branch via {blue ${fstabUrl}} (${resp.status}). Maybe not pushed yet?`);
       } else {
         this.log.warn(chalk`Unable to verify {yellow ${ref}} branch on {blue ${fstabUrl}} (${resp.status}). Fallback to {yellow main} branch.`);
-        this._url = `https://main--${gitUrl.repo}--${gitUrl.owner}.hlx.page`;
+        this._url = `https://main--${gitUrl.repo}--${gitUrl.owner}.${previewHostBase}`;
       }
     }
   }
diff --git a/test/up-cmd.test.js b/test/up-cmd.test.js
index 56bf8b314..adc810746 100644
--- a/test/up-cmd.test.js
+++ b/test/up-cmd.test.js
@@ -65,6 +65,73 @@ describe('Integration test for up command with helix pages', function suite() {
       .get('/not-found.txt')
       .reply(404);
 
+    nock('https://admin.hlx.page:443')
+      .get('/sidekick/dummy-foo/adobe/master/config.json')
+      .reply(404);
+
+    let port;
+    await new Promise((resolve, reject) => {
+      let error = null;
+      cmd
+        .on('started', async () => {
+          try {
+            port = cmd.project.server.port;
+            let ret = await assertHttp(`http://127.0.0.1:${port}/index.html`, 200);
+            assert.strictEqual(ret.trim(), '## Welcome');
+            ret = await assertHttp(`http://127.0.0.1:${port}/local.txt`, 200);
+            assert.strictEqual(ret.trim(), 'Hello, world.');
+            await assertHttp(`http://127.0.0.1:${port}/not-found.txt`, 404);
+          } catch (e) {
+            error = e;
+          }
+          await cmd.stop();
+        })
+        .on('stopped', () => {
+          if (error) {
+            reject(error);
+          }
+          resolve();
+        })
+        .run()
+        .catch(reject);
+    });
+    assert.strictEqual(opened, `http://localhost:${port}/`);
+  });
+
+  it('up command opens browser and delivers correct response on helix 5.', async () => {
+    let opened;
+    const MockedCommand = await esmock('../src/up.cmd.js', {
+      '../src/abstract-server.cmd.js': await esmock('../src/abstract-server.cmd.js', {
+        open: (url) => {
+          opened = url;
+        },
+      }),
+    });
+    initGit(testDir, 'https://github.com/adobe/dummy-foo.git');
+    const cmd = new MockedCommand()
+      .withLiveReload(false)
+      .withDirectory(testDir)
+      .withOpen('/')
+      .withHttpPort(0);
+
+    nock('https://master--dummy-foo--adobe.aem.page')
+      .get('/fstab.yaml')
+      .reply(200, 'dummy')
+      .get('/index.html')
+      .reply(200, '## Welcome')
+      .get('/not-found.txt')
+      .reply(404);
+
+    nock('https://admin.hlx.page:443')
+      .get('/sidekick/dummy-foo/adobe/master/config.json')
+      .reply(200, {
+        host: 'example.com',
+        liveHost: 'master--dummy-foo--adobe.aem.live',
+        previewHost: 'master--dummy-foo--adobe..aem.page',
+        project: 'Example Project on Helix 5',
+        testProperty: 'header',
+      });
+
     let port;
     await new Promise((resolve, reject) => {
       let error = null;
@@ -116,6 +183,10 @@ describe('Integration test for up command with helix pages', function suite() {
       .get('/not-found.txt')
       .reply(404);
 
+    nock('https://admin.hlx.page:443')
+      .get('/sidekick/dummy-foo/adobe/tripod/test/config.json')
+      .reply(404);
+
     cmd
       .on('started', async () => {
         try {
@@ -160,6 +231,10 @@ describe('Integration test for up command with helix pages', function suite() {
       .get('/fstab.yaml')
       .reply(404, 'dummy');
 
+    nock('https://admin.hlx.page:443')
+      .get('/sidekick/dummy-foo/adobe/master/config.json')
+      .reply(404);
+
     cmd
       .on('started', async () => {
         try {
@@ -208,6 +283,14 @@ describe('Integration test for up command with helix pages', function suite() {
       .get('/fstab.yaml')
       .reply(200, 'yep!');
 
+    nock('https://admin.hlx.page:443')
+      .get('/sidekick/dummy-foo/adobe/master/config.json')
+      .reply(404);
+
+    nock('https://admin.hlx.page:443')
+      .get('/sidekick/dummy-foo/adobe/new-branch/config.json')
+      .reply(404);
+
     let timer;
     cmd
       .on('started', async () => {
@@ -257,6 +340,14 @@ describe('Integration test for up command with helix pages', function suite() {
       .get('/fstab.yaml')
       .reply(404, 'dummy');
 
+    nock('https://admin.hlx.page:443')
+      .get('/sidekick/dummy-foo/adobe/master/config.json')
+      .reply(404);
+
+    nock('https://admin.hlx.page:443')
+      .get('/sidekick/dummy-foo/adobe/new-and-totally-unreasonably-long-in-fact-too-long-branch/config.json')
+      .reply(404);
+
     let timer;
     cmd
       .on('started', async () => {
@@ -336,6 +427,10 @@ describe('Integration test for up command with cache', function suite() {
       .get('/head.html')
       .reply(200, '<link rel="stylesheet" href="/styles.css"/>');
 
+    nock('https://admin.hlx.page:443')
+      .get('/sidekick/dummy-foo/adobe/master/config.json')
+      .reply(404);
+
     nock.enableNetConnect(/127.0.0.1/);
 
     cmd