1)In Your client machine(LAN)you have to run FTP server

2)In router configure Trigger port 443:443 and Target port 21:21

3)External network(WAN) try to access ftp server of client machine using router uplink ip address(Goto terminal enter ftp -p 192.168.2.30)   ftp port 21 will not start util you trigger any packet flow on port 443 in your client machine
4)In your client machine(LAN)run https service(In browser https://www.google.com)
5)Goto to your external network(WAN),try access ftp server of client machine(ftp -p 192.168.2.30).incoming traffic on ports 21 after seeing an outgoing packet on port 443

UDP - The Netcat (nc) command is a command-line utility for reading and writing data between two computer networks. The communication happens using either TCP or UDP

1)In router configure Trigger port 443:443 and Target port 2399:2399

2)In Your client machine(LAN)you have to run : nc -u -l 2399
3)From external WAN machine run nc -u 192.168.2.30 2399 (192.168.2.30 - router uplink ip address) 
4)In your client machine(LAN)run https service(In browser https://www.google.com)
5)Goto to your external network(WAN), access server of client machine(Try sending some packets to wan client). Able to see incoming traffic on ports 2399 after seeing an outgoing packet on port 443