diff --git a/plugins/printers/api/asset_routes.py b/plugins/printers/api/asset_routes.py
index d45401b..6ad1c21 100644
--- a/plugins/printers/api/asset_routes.py
+++ b/plugins/printers/api/asset_routes.py
@@ -364,12 +364,29 @@ UNIVERSAL_INSTALL_VENDORS = frozenset({'HP', 'Xerox'})
 
 def _batch_base_url():
     """Base URL the generated .bat downloads installers from. Prefer the
-    configured site_base_url (already includes the /shopdb mount); fall back to
-    the request root so a site that never set it still produces a usable batch."""
+    configured site_base_url (it already includes scheme + the /shopdb mount).
+
+    Fallback matters: behind IIS the app sees http on a loopback port and its
+    url_root drops the mount, so a naive request.url_root yields a broken
+    http://127.0.0.1/installers/... URL. Rebuild from the forwarded Host + the
+    mount (script_root) and force https instead."""
     base = (Setting.get('site_base_url') or '').strip().rstrip('/')
     if base:
         return base
-    return request.url_root.rstrip('/')
+    host = request.headers.get('X-Forwarded-Host') or request.host
+    root = (request.script_root or '').rstrip('/')
+    return 'https://%s%s' % (host, root)
+
+
+def _printer_vendor(printer):
+    """Vendor name for install grouping. The legacy import sets the printer's
+    model but not its direct vendorid, so resolve via the model's vendor (as the
+    classic installprinter.asp did) when the printer has no direct vendor."""
+    if printer.vendor:
+        return (printer.vendor.vendor or '').strip()
+    if printer.model and printer.model.vendor:
+        return (printer.model.vendor.vendor or '').strip()
+    return ''
 
 
 def _installer_url(installpath, base):
@@ -429,7 +446,7 @@ def printer_install_batch():
         name = _install_name(printer, asset)
         if not name:
             continue
-        vendor = (printer.vendor.vendor if printer.vendor else '').strip()
+        vendor = _printer_vendor(printer)
         installpath = (printer.installpath or '').strip()
         if vendor in UNIVERSAL_INSTALL_VENDORS:
             universal.append(name)
diff --git a/tests/test_plugins/test_printer_install_batch.py b/tests/test_plugins/test_printer_install_batch.py
index 7d71356..e0c5eb6 100644
--- a/tests/test_plugins/test_printer_install_batch.py
+++ b/tests/test_plugins/test_printer_install_batch.py
@@ -72,6 +72,33 @@ def test_install_batch_groups_universal_specific_and_manual(
     assert 'c350navi.zip' not in bat  # never handed to the runner
 
 
+def test_install_batch_resolves_vendor_via_model(
+        client, db, auth_headers, printer_assettype):
+    """A printer with no direct vendorid still groups as universal when its
+    MODEL's vendor is HP/Xerox (the import sets the model, not the printer's
+    vendorid) - the bug that dumped every prod printer into 'manual (unknown)'."""
+    from shopdb.core.models import Vendor, Model
+
+    xerox = Vendor(vendor='Xerox')
+    db.session.add(xerox)
+    db.session.commit()
+    model = Model(modelnumber='VersaLink C7125', vendorid=xerox.vendorid)
+    db.session.add(model)
+    db.session.commit()
+
+    # No vendorid on the printer - only the model ties it to Xerox.
+    pid = _make_printer(client, auth_headers, assetnumber='SpoolsInspection-Xerox',
+                        hostname='wjprn07', modelnumberid=model.modelnumberid)
+
+    resp = client.get('/api/printers/install-batch?printerids=%d' % pid,
+                      headers=auth_headers)
+    assert resp.status_code == 200
+    bat = resp.get_data(as_text=True)
+    assert 'PrinterInstaller.exe' in bat
+    assert '/PRINTER="SpoolsInspection-Xerox"' in bat
+    assert 'MANUAL' not in bat
+
+
 def test_install_batch_requires_ids(client, db, auth_headers, printer_assettype):
     resp = client.get('/api/printers/install-batch', headers=auth_headers)
     assert resp.status_code == 400