Go to Report > Bandwidth > Historic Top User
Select date range and type download or upload. Copy target username and go to “Account > User > Search” username and view user details by clicking the icon
Copy user MAC address from user details overview tab.
After copying user MAC address, go to “Policy > Firewall > Create Policy“, proceed to fill all required info and
NAS: Select All
Host/MAC: User MAC Address
Policy: Select “Block the MAC Address”
You are now DONE and set to go!