[fix] Too late to write a good comment

conf/ynh-vpnclient

@@ -61,7 +61,7 @@ has_nativeip6() {
 }
 
 has_ip6delegatedprefix() {
-  [ "${ynh_ip6_addr}" != none ]
+  [ "${ynh_ip6_addr}" != none ] && [ "${ynh_ip6_addr}" != "" ]
 }
 
 is_ip6addr_set() {

config_panel.toml

@@ -91,7 +91,7 @@ name = "DNS & IPv6"
         type = "tags"
         optional = true
         visible = "dns_method == 'custom'"
-        pattern.regexp = "^([0-9.]{8,16}|[0-9a-fA-F:]+)$"
+        pattern.regexp = "^([0-9.]{7,15}|[0-9a-fA-F:]+)$"
         pattern.error = "Not an ip"
         
     [advanced.ipv6]