Ok.....

I have:

2 phone jacks in the house (filters on each)
1 phone line coming into the house (nothing else on the line, faxes, answering machines etc.)
A 502T xtra supplied modem that works

Problem: I am testing a linksys AM300 and linksys RV042 and I have no internet connection.

Setup:

Am300
--------
LAN IP = 192.168.12.1
subnet = 255.255.255.0

RV042
-------
LAN IP = 192.168.30.1
subnet = 255.255.255.0

Ethernet cable from AM300 Internet port to RV042 WAN1 port
Ethernet cable from RV042 LAN1 port to PC NIC

The AM300 is running PPPoA in half bridge mode into the RV042, the AM300 receives IP settings from xtra.
eg:

125.146.67.125
255.0.0.0
125.146.56.423

It passes on the following to the RV042.
eg:

125.146.67.125
255.255.255.255
125.146.56.423

The only difference is the subnet.

Can not even ping internet IP addresses from inside RV042.

Things I have tried:

Different filters.
Different ethernet cables.
Different RJ12 cables.
Unplugged the other phone jack.
Moved the setup to the other phone jack.
Latest firmware.
Disable firewalls everywhere.

Took the AM300 and RV042 to work, it worked with the exact same setup. ISP is xtra on pro plan with static IP.
Took the AM300 and RV042 to another house, it worked with the exact same setup. ISP is slingshot with dynamic IP.
Replaced the AM300 with a D-Link DSL-302G in half bridge mode, subnet given to RV042 was 255.0.0.0
Set the AM300 to full PPPoA mode and I had internet connection. (RV042 needs half bridge to work)
Plugged 2 other laptops into the RV042, no internet connection.

From memory:

Slingshot gave the RV042 a subnet of 255.255.255.240 or something like that and I can not remember what subnet was given to the RV042 at work.

I have tried everything I can think of, is this a subnert issue? An ISP plan issue? HOuse wiring issue?

Help and thanks.