Connecting an external router to the
Verizon Westell 6100 DSL modem-router.

    Verizon DSL modem-routers have some kind of configuration system where they automatically connect to Verizon and configure themselves.  Unfortunately, in my experience, they are pretty much impossible to configure manually.  I do not know why but I have never been able to configure one manually and if the automatic system does not work you are pretty much stuck.  This has been my experience repeatedly with Verizon modems.
    In this particular case the installation was giving problems with bad connections, etc.  I analyzed it and it had a Westell 6100 DSL modem-router and, connected to it, an Airlink 101 - AR430W wireless access point and router.  The problem was that the two routers were connected in series so that there were two NATs to be traversed and an unnecessary intermediate LAN.  This was the cause of lost packets, failed connections and other troubles.  Of course, this is the simplest way to do it and it will work although not as well as other configurations but if you don't want to do any configuration this should work right out of the box.  Just plug the router into the modem.

Verizon Westell 6100 DSL modem router network LAN with AR430w wifi ap & router


    The logical and best way to do it is to configure the modem as a pure bridge as is explained in this page of dslreports.  The configuration then would look like this:

Verizon Westell 6100 DSL modem router network LAN with AR430w wifi ap & router
    If you can get it to work that is the best configuration but unfortunately, after many hours of trying I still could not get it to work and I have no idea why but I have a feeling the quirky Verizon connection is at fault and I could not set up manually the PPP client in the AR430W to work with the Westell modem and the Verizon connection.  I have done similar configurations with generic modems and other DSL suppliers but with Verizon I have had nothing but trouble (NBT).
    After some hours I gave up on trying to get that configuration to work and I had the idea of bypassing the NAT of the AR430W access point.  I would use it as a switch and not as a router.  This is what the configuration looks like:
Verizon Westell 6100 DSL modem router network LAN with AR430w wifi ap & router
    Note that now the Westell modem LAN and the Airlink AR430W router LAN are one and the same so the local address of the Westell has to be changed from the default which is now in conflict with the Westell modem which is using that same address.  I changed the address of the AR430W to     The DHCP server of the AR430W router is disabled because it does not know where the gateway is and it would not work if enabled.  Instead the DHCP server of the Westell modem is left enabled and it will assign IP addresses correctly and use the correct gateway (itself).  Another option, of course, is to configure the computers' connections manually with gateway
    This configuration is working fine and has the advantage that you do not need to change anything in the configuration of the Westell 6100 modem which is configured the same way it was initially.  This configuration is much simpler to set up and troubleshoot than the one I could not get to work.  In this case you can test the modem independently and then connect the auxiliary router configured as a switch but in the configuration recommended by dslreports both devices need to be configured correctly and if the setup is not working it is difficult or impossible to determine which of the two is at fault.

Last updated 2011/04/23