diff --git a/deploy/docker/Dockerfile b/deploy/docker/Dockerfile
index 79f7813ea..5213579a7 100644
--- a/deploy/docker/Dockerfile
+++ b/deploy/docker/Dockerfile
@@ -50,9 +50,8 @@ VOLUME ["/opt/emqx/log", "/opt/emqx/data"]
 # - 11883 port for internal MQTT/TCP
 # - 18083 for dashboard
 # - 4370 default Erlang distrbution port
-# - 5369 for gen_rpc port mapping
-# - 6369 6370 for distributed node
-EXPOSE 1883 8081 8083 8084 8883 11883 18083 4370 5369 6369 6370
+# - 5369 for backplain gen_rpc
+EXPOSE 1883 8081 8083 8084 8883 11883 18083 4370 5369
 
 ENTRYPOINT ["/usr/bin/docker-entrypoint.sh"]
 
diff --git a/deploy/docker/Dockerfile.alpine b/deploy/docker/Dockerfile.alpine
index 9426cc6ab..a8aee2f50 100644
--- a/deploy/docker/Dockerfile.alpine
+++ b/deploy/docker/Dockerfile.alpine
@@ -68,9 +68,8 @@ VOLUME ["/opt/emqx/log", "/opt/emqx/data"]
 # - 11883 port for internal MQTT/TCP
 # - 18083 for dashboard
 # - 4370 default Erlang distrbution port
-# - 5369 for gen_rpc port mapping
-# - 6369 6370 for distributed node
-EXPOSE 1883 8081 8083 8084 8883 11883 18083 4370 5369 6369 6370
+# - 5369 for backplain gen_rpc
+EXPOSE 1883 8081 8083 8084 8883 11883 18083 4370 5369
 
 ENTRYPOINT ["/usr/bin/docker-entrypoint.sh"]
 
diff --git a/deploy/docker/docker-entrypoint.sh b/deploy/docker/docker-entrypoint.sh
index cabe69ead..4b1eced8c 100755
--- a/deploy/docker/docker-entrypoint.sh
+++ b/deploy/docker/docker-entrypoint.sh
@@ -61,6 +61,7 @@ fill_tuples() {
 # having static node names. So it's troulbe-free for multiple emqx nodes
 # running on the same host.
 # When start emqx in docker, it's mostly one emqx node in one container
+# i.e. use port 5369 (or per tcp_server_port | ssl_server_port config) for gen_rpc
 export EMQX_RPC__PORT_DISCOVERY="${EMQX_RPC__PORT_DISCOVERY:-manual}"
 
 exec "$@"