Multiple (over 3) connection

Hi
I'd like to connection to my target PC with 3 steps by WinSCP.

MyPC -> "COM server"(port:9022) -> Server1(port:22) -> Server2(port:22)
*My target PC is Server2 and I necessarily need to connection to "COM server" and Server1.

How do I use WinSCP to use 3 step's connection?

p.s.
I tried to use Tunnel's function , but I can't do mutiple(NOT 2) connection.
Only if I want to connect to Server1 via "COM server", I can connect by using Tunnel's function.
If I want to connect to Server2 via "COM server" and Server1, I can NOT connect by using Tunnel's function.

Thank you.

Please read documentation:
https://winscp.net/eng/docs/guide_tunnel