Setting: "Make controller discoverable on L2 network"?

[BKRonline]

Hello,

In the cloud key controller what is the setting "Make controller discoverable on L2 network" under Settings > Controller > Controller Settings?

On an older site it's unchecked, and on a newer site it's checked. The newer site is in a double NAT situation, and I don't think I touched either one of these settings on either site.

So, what does it mean, and how do I know when to enable or disable it?

[sydude]

I have the same question.. It's a pretty prominent setting with evidently serious consequences that isn't widely documented in a way that non-networking experts can understand. 

[ChrisFD2]

https://community.ubnt.com/t5/UniFi-VoIP/Version-4-5-2-gt-Make-controller-discoverable-on-L2-Network...

[klapppa]

That didn't explain anything. What does it do?

[blackglove9]

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@klapppa wrote:
That didn't explain anything. What does it do?

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That link does explain it: 

"BTW, this feature is about controller's visibility and is unrelated to device management.

When it's enabled, you can find the "controller" (via mDNS query) if you are on the same L2 network."

Do you understand what an L2 network is and what mDNS is?