diff --git a/content/en/docs/setup/independent/create-cluster-kubeadm.md b/content/en/docs/setup/independent/create-cluster-kubeadm.md
index a91c7e25b1..161a3d864a 100644
--- a/content/en/docs/setup/independent/create-cluster-kubeadm.md
+++ b/content/en/docs/setup/independent/create-cluster-kubeadm.md
@@ -340,6 +340,10 @@ Set `/proc/sys/net/bridge/bridge-nf-call-iptables` to `1` by running `sysctl net
 to pass bridged IPv4 traffic to iptables' chains. This is a requirement for some CNI plugins to work, for more information
 please see [here](/docs/concepts/cluster-administration/network-plugins/#network-plugin-requirements).
 
+Make sure that your firewall rules allow UDP ports 8285 and 8472 traffic for all hosts participating in the overlay network.
+see [here
+](https://coreos.com/flannel/docs/latest/troubleshooting.html#firewalls).
+
 Note that `flannel` works on `amd64`, `arm`, `arm64`, `ppc64le` and `s390x` under Linux.
 Windows (`amd64`) is claimed as supported in v0.11.0 but the usage is undocumented.