diff --git a/documentation/README.md b/documentation/README.md
index 24cdbb9..e00caed 100644
--- a/documentation/README.md
+++ b/documentation/README.md
@@ -33,6 +33,7 @@ minimum configuration.
   - [Provision multiple standalone k3s nodes](configuration/multiple-standalone-k3s-nodes.md)
   - [Set node labels and component arguments](configuration/node-labels-and-component-args.md)
   - [Use an alternate CNI](configuration/use-an-alternate-cni.md)
+  - [IPv4/IPv6 Dual-Stack config](configuration/ipv4-ipv6-dual-stack.md)
   - [Start K3S after another service](configuration/systemd-config.md)
 
 ### Operations
diff --git a/documentation/configuration/ipv4-ipv6-dual-stack.md b/documentation/configuration/ipv4-ipv6-dual-stack.md
new file mode 100644
index 0000000..fc80c8e
--- /dev/null
+++ b/documentation/configuration/ipv4-ipv6-dual-stack.md
@@ -0,0 +1,21 @@
+# IPv4 and IPv6 Dual-stack config
+
+If you need to run your K3S cluster with both IPv4 and IPv6 address ranges
+you will need to configure the `k3s_server.cluster-cidr` and
+`k3s_server.service-cidr` values specifying both ranges.
+
+:hand: if you are using `k3s<1.23` you will need to use a different CNI as
+dual-stack support is not available in Flannel.
+
+Below is a noddy example:
+
+```yaml
+---
+
+k3s_server:
+  # Using Calico on k3s<1.23 so Flannel needs to be disabled.
+  flannel-backend: 'none'
+  # Format: ipv4/cidr,ipv6/cidr
+  cluster-cidr: 10.42.0.0/16,fc00:a0::/64
+  service-cidr: 10.43.0.0/16,fc00:a1::/64
+```
diff --git a/vars/main.yml b/vars/main.yml
index bf8b80d..88664ed 100644
--- a/vars/main.yml
+++ b/vars/main.yml
@@ -120,9 +120,9 @@ k3s_config_exclude:
     correction: k3s_token_location
 
 # Config items and the versions that they were introduced
-# k3s_config_version_check:
-#   - setting: example
-#     version: 1.19.3
+k3s_config_version_check:
+  - setting: etcd-s3-bucket
+    version: 1.20.6  # Prior to this there was very buggy support!
 
 # Config items that should be marked as experimental
 k3s_experimental_config: