kubernetes/talos/patches/k8s-1.yaml

@@ -20,6 +20,29 @@ machine:
     # un-translated SYN-ACK -> client kernel RST, verified live 2026-07-23).
     # This disables v6 entirely on that link, including link-local.
     net.ipv6.conf.ens19.disable_ipv6: "1"
+    # Same argument, applied to the physical ports rather than a VLAN child.
+    #
+    # enp2s0f0np0 is nothing but the trunk parent for mgmt0 and ens19, and
+    # enp87s0 is unused. Both sit on the untagged fallback network, where by
+    # design nothing is supposed to run — and both were autoconfiguring
+    # themselves from its router advertisements: an fd00::/64 ULA each, plus
+    # an IPv6 default route each.
+    #
+    # The result was four IPv6 default routes per node at identical priority
+    # 1024 — mgmt0, enp2s0f0np0, enp87s0 and lo — of which only mgmt0 has a
+    # globally routable source address. With nothing to break the tie,
+    # outbound IPv6 mostly left through an interface whose only usable source
+    # was a ULA, so the cluster had no IPv6 egress at all while IPv4 worked
+    # normally. It surfaced as two NetBird probes reporting the proxies down
+    # for 30 hours; the proxies were fine and answered IPv6 in 13 ms from
+    # outside.
+    #
+    # Verified on k8s-1 before rolling to the others: disabling v6 on a VLAN
+    # parent leaves the VLAN child alone. mgmt0 kept its global address and
+    # its fd40:: address, Ceph did not notice, and every failing probe
+    # recovered on the next scrape.
+    net.ipv6.conf.enp2s0f0np0.disable_ipv6: "1"
+    net.ipv6.conf.enp87s0.disable_ipv6: "1"
   install:
     # Three NVMe drives are ordinary block devices to Talos here: the Kingston
     # OM8PGP41024Q-A0 system disk, the Samsung PM983 that Rook claims as the

kubernetes/talos/patches/k8s-2.yaml

@@ -9,6 +9,15 @@ machine:
     # macvlan parent for the v30iot pod attachments; host addresses on that L2
     # make node replies bypass the UDM and break every UDM-DNATed flow.
     net.ipv6.conf.ens19.disable_ipv6: "1"
+    # Same argument for the physical ports: enp2s0f0np0 is only the trunk
+    # parent for mgmt0 and ens19, enp87s0 is unused, and both sit on the
+    # untagged fallback network where nothing is supposed to run. Both were
+    # taking an fd00::/64 and an IPv6 default route from its router
+    # advertisements, leaving four equal-priority default routes per node of
+    # which only mgmt0 has a globally routable source. See k8s-1.yaml for the
+    # full reasoning and how it was verified.
+    net.ipv6.conf.enp2s0f0np0.disable_ipv6: "1"
+    net.ipv6.conf.enp87s0.disable_ipv6: "1"
   install:
     # Three NVMe drives are visible on bare metal. Select the installer target
     # by serial so it cannot land on the OSD drive or on EPHEMERAL, whatever

kubernetes/talos/patches/k8s-3.yaml

@@ -8,6 +8,15 @@ machine:
   sysctls:
     # v30iot NIC carries no host addressing — see k8s-1.yaml.
     net.ipv6.conf.ens19.disable_ipv6: "1"
+    # Same argument for the physical ports: enp2s0f0np0 is only the trunk
+    # parent for mgmt0 and ens19, enp87s0 is unused, and both sit on the
+    # untagged fallback network where nothing is supposed to run. Both were
+    # taking an fd00::/64 and an IPv6 default route from its router
+    # advertisements, leaving four equal-priority default routes per node of
+    # which only mgmt0 has a globally routable source. See k8s-1.yaml for the
+    # full reasoning and how it was verified.
+    net.ipv6.conf.enp2s0f0np0.disable_ipv6: "1"
+    net.ipv6.conf.enp87s0.disable_ipv6: "1"
   install:
     # Three NVMe drives are visible on bare metal. Select the installer target
     # by serial so it cannot land on the OSD drive or on EPHEMERAL, whatever