PPPoE stands for Point to Point Protocol over Ethernet, unless you did something horribly wrong that cable going from your modem to your router
is an Ethernet cable which is why you're using it on the router as opposed to PPPoA on the modem which is attached to your isp. As for the discrepancy of isp on the 855, well it's most likely an oversight, you see the actual hardware is identical across the globe but firmware differs for the local broadcasting laws, Japan has 20 channels, UK 11 and US 6 (or something like that). Also for what it's worth, unless you really don't know what you're doing it's simplest avoiding the wizards, they cause more problems than they solve and the 855 has more than one glitch in it.
First is the
firmware up to date? If it is resetting the modem and beginning again is the easiest route, but plug the Ethernet line from your pc into it and log in manually and put the setting you need in, reboot and see if you can get a connection. If you do change it to bridged making sure to disable everything else (DHCP server, QOS etc.) and reboot.
Now plug it into the router, connect your pc to the router, manual internet set-up and chose PPPoE and put the settings in, make sure the router is acting as the DHCP server, and it
should work. If it's not then it's possible your isp is one of those that locks the line to the MAC address of the first machine (or router) in which case you'll need to clone your pcs address or that rotuer/modem you were using previously.
The one real advantage of the using the crappy modems isp hand out is that everything's pre-set and all you need to do it press the bridge button
