IP 255.255.255.255

The firewall cannot allow Broadcast packets. Broadcast Packets is something special, as it will be send to all clients. 

You cannot allow broadcast packets to be send to some other interface. This is not possible on SFOS. 

Hi.

further to LuCar's answer what is actually them address the device attempts to talk to, is it on your LAN or on the internet?

Ian

The device is on my LAN.

Then you can ignore the 255,255.255.255 traffic, as LuCar Toni advised it is broadcast traffic, goes everywhere in your network. So what is the device trying to connect to?

ian

Have you checked the log?
Unifi devices tend to connect to [sub].ui.com. I.e. protect.ui.com or UniFi.ui.com

Any problems here?

Yes, I've tried, but it didn't works.

Any other solution?

If I don't allow this 10001 UDP port, I can't use some tools like Ubiquiti Discovery and app WiFiman.

Running those tools in my network, did not have to create bypass rule or anything

Hi,

how many networks do you have that have unified devices on them?

Are your networks through switches?

From what Peter-Paul Gras is advising that all your unified devices need to be on the same network. I run a couple of Unifi APs and a unified controller on two networks without any issues.

Ian