Hi Aero_Ramon,
This option is not available yet. In this post: http://community.cambiumnetworks.com/t5/Your-Ideas/Link-Enable-Disable-Option/idi-p/37341, Seth explains a firewall setting that can enable/disable LAN access on the SM. However, I can see from that post that it is not working for you in NAT mode. We will post another set of firewall rules early next week to enable/disable access through the LAN side when NAT is enabled on the SM.
Thanks,
Sriram