diff --git a/html/cgi-bin/firewall.cgi b/html/cgi-bin/firewall.cgi
index 499f279..d17afab 100644
--- a/html/cgi-bin/firewall.cgi
+++ b/html/cgi-bin/firewall.cgi
@@ -757,6 +757,7 @@ sub checkrule
 				}
 			}
 			if($fwdfwsettings{'nat'} eq 'dnat' && $fwdfwsettings{'dnatport'} eq ''){$fwdfwsettings{'dnatport'}=$custsrvport;}
+			if($fwdfwsettings{'nat'} eq 'dnat' && $fwdfwsettings{'grp3'} eq 'cust_srv'){$fwdfwsettings{'dnatport'}=$custsrvport;}
 		}
 		#check if DNAT port is multiple
 		if($fwdfwsettings{'nat'} eq 'dnat' && $fwdfwsettings{'dnatport'} ne ''){