Remote backup with closed port 22

I have two WD MyCloud devices. Both are EX4100.

I would like to, every day, backup my first device (source) to my second (destination) device.

I tried to use the “Remote backup” app provided by MyCloud. However I have a problem that on the destination device’s network, port 22 is blocked. It is not possible to connect to SSH using XXX.XX.XX.XX:22.

I have therefore setup a port forwarding on the destination device. This means from the outside it is possible to connect using XXX.XX.XX.XX:24.

However, using the remote backup app, it is not possible to specify which port to connect to. How can I do this? Is there some way to specify that I want to connect to XXX.XX.XX.XX:24?