diff --git a/config/net/serv.nix b/config/net/serv.nix
index fc25d10..a31b604 100644
--- a/config/net/serv.nix
+++ b/config/net/serv.nix
@@ -81,6 +81,8 @@
       prometheus = "172.20.73.75";
       oxigraph = "172.20.73.76";
       drone = "172.20.73.77";
+      # !!! IMPORTANT !!!
+      # reuse a `used*` address from above
     };
     ipv6Router = "serv-gw";
     subnets6.dn42 = "fd23:42:c3d2:582::/64";