fix(lan): warn when auto-detected endpoint IP is in Docker/WSL2 172.16/12 range

Nodes running inside WSL2 or Docker have a virtual network interface whose IP
(172.16-31.x.x) is not reachable from physical machines on the LAN.  The UDP
socket probe for outbound IP returns this virtual IP, which gets registered with
the tracker — causing downstream pipeline hops to time out with "urlopen error
timed out".

_warn_virtual_network_ip() now prints a clear multi-line warning at startup
when the auto-detected advertise IP falls in 172.16.0.0/12, including the
fix: --advertise-host <LAN-ip>.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/node/meshnet_node/startup.py

@@ -179,6 +179,35 @@ def _start_heartbeat(
     return t
 
 
+def _warn_virtual_network_ip(ip: str | None) -> None:
+    """Print a warning when the auto-detected advertise IP is in a known virtual-network range.
+
+    172.16.0.0/12 is used by Docker, WSL2, and most hypervisors.  Nodes behind these
+    adapters are NOT directly reachable from other physical machines on the LAN, so
+    cross-host pipeline hops will time out.  The user must pass --advertise-host with
+    their actual LAN IP (e.g. 192.168.x.x) to fix this.
+    """
+    if ip is None:
+        return
+    try:
+        parts = [int(p) for p in ip.split(".")]
+        if len(parts) != 4:
+            return
+        a, b = parts[0], parts[1]
+        # 172.16.0.0/12 → 172.16–31.x.x
+        if a == 172 and 16 <= b <= 31:
+            print(
+                f"\n  WARNING: auto-detected endpoint IP {ip} is in 172.16.0.0/12.\n"
+                f"  This range is used by Docker, WSL2, and virtual machines and is\n"
+                f"  NOT reachable from other physical machines on your LAN.\n"
+                f"  Cross-host pipeline hops WILL time out.\n"
+                f"  Fix: pass --advertise-host <your-LAN-ip> (e.g. 192.168.x.x).\n",
+                flush=True,
+            )
+    except Exception:
+        pass
+
+
 def run_startup(
     tracker_url: str,
     port: int = 0,
@@ -224,6 +253,8 @@ def run_startup(
         except Exception:
             advertise_host = socket.getfqdn()
 
+    _warn_virtual_network_ip(advertise_host)
+
     print("Detecting hardware...", flush=True)
     hw = detect_hardware()
     device: str = hw["device"]