From your brief description it seems that your problem could be misconfiguration of the PPPoE parameters. Below is a list of things you can check:
Network location of the PPPoE server – PPPoE server and client need to be part of the same broadcast domain.
Client Wireless IP Assignment: Static or Dynamic (DHCP) – Is the PPPoE server configured to assign an IP address to the PPPoE client? If so, set Client Wireless IP Assignment to DHCP. User/Password (mandatory) – Has an account for this PPPoE client been provisioned in the PPPoE server? Are the credentials correct? Access Concentrator Name – This field is optional and can be left blank. If using it, is the AC Name used by the PPPoE server configured **exactly** the same at the PPPoE client? Service Name – This field is optional and can be left blank. If using it, is the Service Name used by the PPPoE server configured **exactly** the same at the PPPoE client? Authentication Type: PAP, CHAP or both – Does the server support and is it configured to use PAP, CHAP or both authentication types supported by the PPPoE client? PPPoE client does not support any other authentication types (i.e. MSCHAP).
Regarding co-location with a PMP430, plan for some frequency separation between them (no frequency re-use or overlapping channels). Allow at least a channel width between the edge of the channels in use to be on the safe side.