2 mft servers with 1 gateway

Hello,

I have 2 MFT servers behind 1 gateway. I'm not the one who installed this infrastructure.
I recently migrate the few accounts on these servers to another infrastructure, and clean them up for a new project. That is where I noticed something off.

The gateway is redirecting all SFTP connection to the MFT server 2, nothing on the MFT server 1.
The gateway is configured at the global domain level.
I configured the listeners, port 10022 for the server 1, port 20022 for the server 2.

If I change the port for the listeners, using 20022 for server 1, and 10022 for server 2, all sftp connection are redirected to the server 1.
SO my both servers are working well, it's just that the Gateway is only redirecting the connection to the port 20022.

So, my question, is a 2 MFT Servers behind only one Gateway a working infrastructure?
If yes, how should I configure this ?

Thanks in advance for your help,

Regards,