nix.routers.{border,expo}: move to .4 to its scheme makes sense

The 3rd octet in the ipv4 subnet should match the last digit of the
vlan(at least thats what we try to do for consistency when possible)

Author: sarcasticadmin

nix/nixos-modules/routers/border.nix

@@ -169,7 +169,7 @@ in
             matchConfig.Name = "bridge104";
             networkConfig.DHCP = false;
             address = [
-              "172.20.2.1/24"
+              "172.20.4.1/24"
               "2001:470:f026:104::1/64"
             ];
           };

nix/nixos-modules/routers/expo.nix

@@ -322,11 +322,11 @@ in
             enable = true;
             networkConfig.DHCP = false;
             address = [
-              "172.20.2.3/24"
+              "172.20.4.3/24"
               "2001:470:f026:104::3/64"
             ];
             routes = [
-              { Gateway = "172.20.2.1"; }
+              { Gateway = "172.20.4.1"; }
             ];
           };
           "40-vlan105" = {
@@ -391,7 +391,7 @@ in
 
     scale-network = {
       services.frr.enable = true;
-      services.frr.router-id = "172.20.2.3";
+      services.frr.router-id = "172.20.4.3";
       services.frr.broadcast-interface = [
         "bridge104" # border
         "bridge903" # conf

nix/package-sets/scale-nixos-tests/routers.nix

@@ -142,7 +142,7 @@
       # border can ping both routers
       border.succeed("ping -c 5 172.20.1.2")
       border.succeed("ping -c 5 2001:470:f026:901::2")
-      border.succeed("ping -c 5 172.20.2.3")
+      border.succeed("ping -c 5 172.20.4.3")
       border.succeed("ping -c 5 2001:470:f026:104::3")
 
       # conference can ping both routers
@@ -152,7 +152,7 @@
       conference.succeed("ping -c 5 2001:470:f026:903::3")
 
       # expo can ping both routers
-      expo.succeed("ping -c 5 172.20.2.1")
+      expo.succeed("ping -c 5 172.20.4.1")
       expo.succeed("ping -c 5 2001:470:f026:104::1")
       expo.succeed("ping -c 5 172.20.3.2")
       expo.succeed("ping -c 5 2001:470:f026:903::2")
@@ -171,9 +171,9 @@
       border.wait_until_succeeds("ping -c 5 2001:470:f026:903::3", timeout=60)
 
       # conference can reach border-expo link
-      conference.wait_until_succeeds("ping -c 5 172.20.2.1", timeout=60)
+      conference.wait_until_succeeds("ping -c 5 172.20.4.1", timeout=60)
       conference.wait_until_succeeds("ping -c 5 2001:470:f026:104::1", timeout=60)
-      conference.wait_until_succeeds("ping -c 5 172.20.2.3", timeout=60)
+      conference.wait_until_succeeds("ping -c 5 172.20.4.3", timeout=60)
       conference.wait_until_succeeds("ping -c 5 2001:470:f026:104::3", timeout=60)
 
       # expo can reach conference-border link