How to set up several interfaces.

[flac_rules]

I have 4 network ports, one for WAN, one for LAN (which goes to a switch), i want to use a port for my IPTV decoder, to get it to work I need to connect it directly into the router. But what is best practice to set this up? If I set up a dhcp server on the IPTV-interface this seem to cause trouble, even if i set it up to use a different range than the LAN interface. I use 192.168.1.x for IPs on the LAN-interface.