diff --git a/docs/ENVIRONMENT.rst b/docs/ENVIRONMENT.rst
index 4b45798f..d6c40116 100644
--- a/docs/ENVIRONMENT.rst
+++ b/docs/ENVIRONMENT.rst
@@ -80,7 +80,7 @@ Etcdv3
 Environment names for Etcdv3 are similar as for Etcd, you just need to use ``ETCD3`` instead of ``ETCD`` in the variable name. Example: ``PATRONI_ETCD3_HOST``, ``PATRONI_ETCD3_CACERT``, and so on.
 
 .. warning::
-    Keys created with protocol version 2 are not visible with protocol version 3 and the other way around, therefore it is not possible to switch from Etcd to Etcdv3 just by updating Patroni configuration.
+    Keys created with protocol version 2 are not visible with protocol version 3 and the other way around, therefore it is not possible to switch from Etcd to Etcdv3 just by updating Patroni configuration. In addition, Patroni uses Etcd's gRPC-gateway (proxy) to communicate with the V3 API, which means that TLS common name authentication is not possible.
 
 
 ZooKeeper
diff --git a/docs/yaml_configuration.rst b/docs/yaml_configuration.rst
index 0929404d..e54f465b 100644
--- a/docs/yaml_configuration.rst
+++ b/docs/yaml_configuration.rst
@@ -144,7 +144,7 @@ Etcdv3
 If you want that Patroni works with Etcd cluster via protocol version 3, you need to use the ``etcd3`` section in the Patroni configuration file. All configuration parameters are the same as for ``etcd``.
 
 .. warning::
-    Keys created with protocol version 2 are not visible with protocol version 3 and the other way around, therefore it is not possible to switch from ``etcd`` to ``etcd3`` just by updating Patroni config file.
+    Keys created with protocol version 2 are not visible with protocol version 3 and the other way around, therefore it is not possible to switch from ``etcd`` to ``etcd3`` just by updating Patroni config file. In addition, Patroni uses Etcd's gRPC-gateway (proxy) to communicate with the V3 API, which means that TLS common name authentication is not possible.
 
 
 ZooKeeper