I have my network set up as shown in the picture below. I've recently expanded the capability of LMCE system by adding VOIP and a laptop orbiter. While trying to make them work correctly, I've begun to doubt that my network is correctly configured. My DSL modem (Actiontec GT701D) and router (Linksys WRT54G) are very close to their default settings - all I did was set up the DSL modem by selecting PPPoA and entering a username and password. The trouble is that these two devices duplicate many functions. In the default configuration, both are gateways, and both perform DHCP and NAT functions. Although my internet has been working, it seems I've been double natting - apparently a common amateur error. I've been trying to fix this, but no two online articles give the same advice. I've been playing with settings and breaking my system in various ways (no internet, no VOIP, unable to use the laptop orbiter, etc...)
Can anyone steer me in the right direction? It seems that the DSL modem should be my gateway and firewall, and should have NAT and DHCP disabled. The Linksys router should do NAT and DHCP, and should have the gateway and firewall disabled. Do I need to bridge the devices?