fix: wireguard.address must be the router's own address in its network, not the network or broadcast address, from which the peers' addresses are told apart.

README.md

@@ -114,7 +114,7 @@ must have the type shown below; an unknown section or setting is an error.
 | `p2s` | `enabled` | boolean | `false` | Road-warrior access |
 | `p2s` | `address_pool` | string | | CIDR assigned to road-warrior clients |
 | `wireguard` | `enabled` | boolean | `false` | WireGuard endpoint |
-| `wireguard` | `address` | string | | Address and prefix for `wg0`, for example `192.168.200.1/24` |
+| `wireguard` | `address` | string | | The router's own address on `wg0` with the prefix of the peers' network, for example `192.168.200.1/24`; the network and the broadcast address of a network larger than /31 are refused |
 | `wireguard` | `listen_port` | integer | `51820` | UDP port |
 | `openvpn` | `enabled` | boolean | `false` | OpenVPN access for users |
 | `openvpn` | `address_pool` | string | | IPv4 CIDR assigned to OpenVPN clients |

debian-package/debian/changelog

@@ -1,3 +1,13 @@
+vpn-router (0.25.2-1) unstable; urgency=medium
+
+  fix: wireguard.address must be the router's own address in its network, not the network or broadcast address, from which the peers' addresses are told apart.
+
+  * A wireguard.address that is the network or the broadcast address of a
+    network larger than /31, such as 192.168.232.0/24, is refused with the
+    first address of the network as the example.
+
+ -- Slawomir Koszewski <slawek@koszewscy.waw.pl>  Tue, 03 Nov 2026 02:30:00 +0100
+
 vpn-router (0.25.1-1) unstable; urgency=medium
 
   fix: /remote-access gives the router's WireGuard public key, endpoint and allowed IPs, which a peer's configuration needs.

debian-package/src/usr/lib/vpn-router/vpnrouter.py

@@ -458,10 +458,16 @@ def validate(cfg):
     wg_address = _get(cfg, 'wireguard', 'address')
     if wg_address:
         try:
-            ipaddress.ip_interface(wg_address)
+            interface = ipaddress.ip_interface(wg_address)
         except ValueError:
             raise ConfigError(
                 f'wireguard.address: {wg_address!r} is not an address with prefix')
+        # The router's own address on wg0, from which the peers' addresses of the same network are told apart.
+        network = interface.network
+        if network.num_addresses > 2 and interface.ip in (network.network_address, network.broadcast_address):
+            raise ConfigError(
+                f'wireguard.address: {wg_address} is the network or broadcast address of {network}; give the '
+                f'router\'s own address in it, such as {next(network.hosts())}/{network.prefixlen}')
 
     port = _get(cfg, 'wireguard', 'listen_port')
     if not 1 <= port <= 65535: