diff --git a/routlin/install.py b/routlin/install.py
index 7e37bc0..fddee33 100644
--- a/routlin/install.py
+++ b/routlin/install.py
@@ -418,15 +418,28 @@ def setup_caddy(domain, email):
 
 
 def _lan_ip():
-    """Read the LAN IP from routlin's networkd config files."""
+    """Read the LAN IP from routlin's networkd config files.
+
+    Prefers the physical (untagged) interface — its Name has no dot.
+    Falls back to the first address found across all routlin network files.
+    """
     import glob
+    fallback = None
     try:
         for path in sorted(glob.glob("/etc/systemd/network/10-routlin-*.network")):
-            for m in re.finditer(r'^Address=(\d+\.\d+\.\d+\.\d+)/', Path(path).read_text(), re.MULTILINE):
-                return m.group(1)
+            content = Path(path).read_text()
+            name_m  = re.search(r'^Name=(.+)$', content, re.MULTILINE)
+            addr_m  = re.search(r'^Address=(\d+\.\d+\.\d+\.\d+)/', content, re.MULTILINE)
+            if not name_m or not addr_m:
+                continue
+            ip = addr_m.group(1)
+            if '.' not in name_m.group(1).strip():  # physical interface, no dot
+                return ip
+            if fallback is None:
+                fallback = ip
     except Exception:
         pass
-    return "this server"
+    return fallback or "this server"
 
 
 # ===================================================================