diff --git a/doc/POST_UPGRADE.d/15.2.0~ynh1.md b/doc/POST_UPGRADE.d/15.2.0~ynh1.md
index f1b41d9..2b620fe 100644
--- a/doc/POST_UPGRADE.d/15.2.0~ynh1.md
+++ b/doc/POST_UPGRADE.d/15.2.0~ynh1.md
@@ -4,4 +4,6 @@ eg:
 ```
 192.168.0.88:53
 [2981:2cb2:8e86:91f6:4dab:cc4b:2fba:463b]:53
-```
\ No newline at end of file
+```
+
+If your server does not have an IPv6 address, you only need to enter the IPv4 address.
\ No newline at end of file