DHCP just for guest wifi?

[John Does]

I've an RT-AC87U. My network is managed by a server which has already a dhcp server.
I can create a guest network, but I have to allow intranet access to get an ip address.

Is there any option to avoid the internal access, but get an ip. (dhcp only for the guest network)

Thanks

[EDIT]
I'm using Asuswrt-Merlin 380.69

 

[ColinTaylor]

@John Does There's been quite a few threads discussing this sort of thing. Search the Merlin forum and I'm sure you'll find what you want.