From 8560c11afaf3c7c54c5aaad0e6187714d1d18dd3 Mon Sep 17 00:00:00 2001
From: rope <fredrik@nordhammer.it>
Date: Fri, 22 May 2026 09:27:10 +0100
Subject: [PATCH] fix NIC naming: use udev rules instead of .link files

systemd.network.links didn't generate files; use udev extraRules
to pin NIC names to MACs. Also disable networking.useDHCP catch-all
that silently misconfigured the LAN NIC when it got a wrong name.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 hosts/FredOS-Mediaserver.nix |  2 +-
 services/router.nix          | 22 ++++++++--------------
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/hosts/FredOS-Mediaserver.nix b/hosts/FredOS-Mediaserver.nix
index 3f98e1d..f9f3c95 100644
--- a/hosts/FredOS-Mediaserver.nix
+++ b/hosts/FredOS-Mediaserver.nix
@@ -29,7 +29,7 @@
     ];
 
     # Basic networking
-    networking.useDHCP = lib.mkDefault true;
+    networking.useDHCP = lib.mkForce false;
 
     # Allow fred to act as a remote Nix builder (trusted users can import
     # unsigned store paths sent by the build client).
diff --git a/services/router.nix b/services/router.nix
index fde6002..63df5ea 100644
--- a/services/router.nix
+++ b/services/router.nix
@@ -72,24 +72,18 @@ in
       "net.ipv6.conf.all.disable_ipv6" = 1;
     };
 
+    # Pin interface names to MAC addresses so they never swap across boots.
+    # Without this, "eth0" is an unpredictable kernel name that depends on
+    # device probe order — if the NICs swap, the entire LAN/WAN config breaks.
+    services.udev.extraRules = ''
+      SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="6c:0b:84:0c:4c:58", NAME="eth0"
+      SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="6c:0b:84:0c:4c:59", NAME="eno1"
+    '';
+
     # --- Interface configuration ---
     systemd.network = {
       enable = true;
 
-      # Pin interface names to MAC addresses so they never swap across boots.
-      # Without this, "eth0" is an unpredictable kernel name that depends on
-      # device probe order — if the NICs swap, the entire LAN/WAN config breaks.
-      links = {
-        "10-wan" = {
-          matchConfig.MACAddress = "6c:0b:84:0c:4c:59";
-          linkConfig.Name = "eno1";
-        };
-        "20-lan" = {
-          matchConfig.MACAddress = "6c:0b:84:0c:4c:58";
-          linkConfig.Name = "eth0";
-        };
-      };
-
       networks = {
         "10-wan" = {
           matchConfig.Name = "eno1";