My DSL line is plugged into a 5-port 10/100 Linksys switch. Then I have 2 cables going from that port to my internet gateways (1 - a Trendnet 200 Mbps powerline adapter and 2 - a linux PC server which is acting as a router/gateway).
The DSL gives a 192.168.2.3 and 192.168.2.4 ip address to my 722k receivers. Basically they are directly connected to the Internet via the DSL line. My Linux PC router gets a 192.168.2.2 and then I have all my internal laptops, PCs, and wireless connections going through this machine connected via another switch to another NIC in the linux PC.
You could do this an easier way by using the small switch on your internet connection and then putting one of the plugs into a wireless router in the internet port and everything else you have into the wireless routers internal port to separate your network as well.
I have also verified that the 722ks also work directly connected with cables instead of the powerline adapter.
Also, I had everything plugged through the linux box before and wasn't able to keep the connection. The culprit was/is the fact that my linux box was blocking out the Upnp ports and access after a while. Therefore the 722k receivers were losing connection unless they were actively pulling things from the internet.
Now the 722k receivers have a direct shot to the internet and they are extremely happy in regards to downloading programs.
This is great information, but can you please report what models your switch and router are? I'm guessing your "4 port switch" is actually a router. What's an internal router? Is that where your receivers were plugged in before?