Windows has the ability to set the VPI/VCI settings but the Zywall router does not have the ability to set these.
HUH? The ZyXEL Routers I have used and even the Earthlink Supplied ZyXEL units all have a settings page for VPI/VCI in the DSL Modem or the PPPoE would not work.
Aha, you have a E2E (Ethernet to Ethernet) Router that is not a ADSL Modem also. That is why the VPI/VCI is not there as that is a ATM setting for the DSL side of things. You have to also use a DSL Modem or you cannot connect and the DSL Modem holds the VPI/VCI setting.
DSL Modems have the VPI/VCI either stored in a Table to run though to find the Active VC or they are a single setting supplied and entered during initial configuration for PPP (oE or oA).