diff --git a/config/net/priv.nix b/config/net/priv.nix
index 84850a8..4831cc6 100644
--- a/config/net/priv.nix
+++ b/config/net/priv.nix
@@ -16,10 +16,9 @@ lib.mkMerge (
       site.net."priv${toString n}" = {
         dhcp = {
           server = "priv${toString n}-gw";
-          time = 900;
+          time = 300;
           max-time = 60 * 24 * 3600;
           router = "priv${toString n}-gw";
-          updateOnRenewal = true;
         };
         domainName = "priv${toString n}.zentralwerk.org";
         dynamicDomain = true;
diff --git a/nix/lib/config/options.nix b/nix/lib/config/options.nix
index fe04e86..de776c2 100644
--- a/nix/lib/config/options.nix
+++ b/nix/lib/config/options.nix
@@ -96,11 +96,6 @@ let
       type = with types; attrsOf str;
       default = {};
     };
-    updateOnRenewal = mkOption {
-        type = types.bool;
-        default = false;
-        description = "Update DNS entry on renewal";
-    };
   };
 
   netOpts = { name, ... }: {
diff --git a/nix/nixos-module/container/dhcp-server.nix b/nix/nixos-module/container/dhcp-server.nix
index de9c0f7..8d40ddf 100644
--- a/nix/nixos-module/container/dhcp-server.nix
+++ b/nix/nixos-module/container/dhcp-server.nix
@@ -29,10 +29,6 @@ in
       # TODO: use with kea >= 2.5.0
       # ddns-conflict-resolution-mode = "check-exists-with-dhcid";
       ddns-use-conflict-resolution = false;
-      ddns-replace-client-name = "when-not-present";
-      # fix old, wrong or lost dns entries on renewal
-      ddns-update-on-renew = builtins.any (a: a)
-        (concatMapDhcpNets (net: { dhcp, ... }: dhcp.updateOnRenewal));
       expired-leases-processing.hold-reclaimed-time = builtins.foldl' lib.max
         3600 (concatMapDhcpNets (net: { dhcp, ... }: dhcp.max-time));
 
@@ -42,8 +38,8 @@ in
         pools = [ {
             pool = "${dhcp.start} - ${dhcp.end}";
         } ];
-        renew-timer = builtins.ceil (0.5 * dhcp.time);
-        rebind-timer = builtins.ceil (0.85 * dhcp.time);
+        renew-timer = builtins.ceil (.5 * dhcp.time);
+        rebind-timer = builtins.ceil (.85 * dhcp.time);
         valid-lifetime = dhcp.time;
         option-data = [ {
           space = "dhcp4";