That feature is only configurable via the Unleashed CLI and not via GUI
Please refer to this document:https://support.ruckuswireless.com/documents/2595-ruckus-unleashed-200-7-ga-cli-reference-guide
On page 229:
Management Access Control List Commands
Use the following commands to create or configure management ACLs and enter the config-sys-mgmt-acl or configsys-mgmt-acl-ipv6 contexts. These commands must be used from the config-sys context.
mgmt-acl To create or configure a management ACL, use the following command: mgmt-acl WORD
ruckus(config-sys)# mgmt-acl macl1
The management ACL 'macl1' has been created. To save the Management ACL, type 'end' or 'exit'. ruckus(config-mgmt-acl)#
I hope this answers your question,
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