Hi
i want to run Lock On First on CRS326 at port 1
i enabled port lock and Lock On First and connected a pc to port 1 but after connecting new device to port 1 also new device can connected to network 
what is the problem ??
SwitchOS or RouterOS? I would assume SwirchOS since you asked in that section of the forum - but you know what you get by assuming…
What software version?
Swos version 2.16
A misunderstanding of the feature, that’s what’s wrong, I think.
Lock On First - Allows to learn source MAC address from the first received frame, this property should be used together with Port Lock.
Learning of the first MAC address will reset every time an interface status changes
Disconnect/connect new device = port status change = new first MAC address.
I saw this article but Lock On First dose not work true
Lock On First - Allows to learn source MAC address from the first received frame, this property should be used together with Port Lock. Learning of the first MAC address will reset every time an interface status changes
How exactly do you connect the new device to same port? Do you disconnect the first device? In which case the feature works as intended (it’s designed against connecting a downstream switch/AP to a port).