Hi Lior,
In the same document it is defined that "You can create up to 32 port forwarding rules".
http://docs.ruckuswireless.com/unleashed/200.5/#t-PortForwarding.htmlPort range is not supported, you have to define one port forwarding per rule and that is a limitation.
Regards,
Syamantak Omer
Syamantak Omer | Community moderator | Staff TSE | CWNA | CCNA | RASZA | RICXI | Follow me at https://linkedin.com/in/syamantak-omer-5949b6124