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.

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: