Allow LAN but block internet access

I use a Mango. I want to block internet access to one special client, but the client has to be allowed to login the local network. How can I configure that? If I use the “block” switch in the menu “clients” then the whole network access (also LAN) is blocked, so that doesn’t work.

A trick:

Set up vpn and vpn policy. Only allow this device to access vpn. Then make a vpn that is not connected.

Thanks, alzhao, that’s a very good trick, but it doesn’t work here. The device that I mean cannot access to VPNs (it’s an inverter for a photovoltaic system).

Do you want this device be discovered on your local network only?

Yes, thats it. Other devices in the LAN have to connect to the inverter.

If you have a block device in the client list, the device can be found in the LAN, but the Internet is not accessible.