Combining modem/router (non-DDWRT) with DD-WRT router

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jandot
DD-WRT Novice


Joined: 09 Jan 2018
Posts: 4

PostPosted: Wed Jan 10, 2018 8:49    Post subject: Combining modem/router (non-DDWRT) with DD-WRT router Reply with quote
Hi all,

For my internal network at home, I require that IP addresses of my devices don't change (home automation purposes). Unfortunately, the modem/router provided by the ISP (sagem) does not allow that. Therefore I got hold of a second router (no modem): Linksys E1200. I installed DD-WRT (v3.0-r29519) on the Linksys. Both routers are placed right next to each other.

My question is: what should be the basic setup for connecting the two, and having the Linksys DD-WRT router provide the IP addresses rather than the sagem. I guess this means basically considering the sagem as a modem rather than a modem/router.

Reading quite a bit on different setups of routers and modems (including these forums), this leaves me a bit flabbergasted, unfortunately. (Access points vs bridges vs ...; local IP vs WAN IP; can the dd-wrt router still get an IP address if DHCP on the first router is switched off; etc.)

Could someone indicate how to set such system up?

Code:

--internet----[sagem modem/router]----[dd-wrt router]
                                                                         |    |    |
                                                                         |    |    device C
                                                                         |    device B
                                                                         device A
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jandot
DD-WRT Novice


Joined: 09 Jan 2018
Posts: 4

PostPosted: Wed Jan 10, 2018 10:32    Post subject: Current settings on the dd-wrt router Reply with quote
At the moment the wire from the sagem modem/router goes into one of the 4 ethernet connections in the dd-wrt router instead of the into the single "internet"-labeled jack. These are the current (I think relevant) settings on the dd-wrt router:


    * Setup -> Basic Setup

      * Connection type: disabled
      * Router IP

        * Local IP address: 192.168.1.100 (because DHCP server on sagem IP range ends at 63)
        * Subnet mask: 255.255.255.0
        * Gateway: 192.168.1.1 (= IP of sagem modem)
        * Local DNS: 192.168.1.1 (idem)

      * Network Address Server Settings (DHCP)

        * DHCP Type: DHCP Server
        * DHCP Server: Enabled
        * Start IP address: 192.168.1.101
        * Static DNS 1: 192.168.1.1 (= IP of sagem modem)
        * other static DNS: all 0.0.0.0


    * Wireless -> Basic Settings

      * Wireless Mode: AP
      * Wireless Network Mode: Mixed
      * Network configuration: Bridged

jandot
DD-WRT Novice


Joined: 09 Jan 2018
Posts: 4

PostPosted: Fri Jan 12, 2018 9:55    Post subject: Partly solved => now LAN ports do not work (but wifi does Reply with quote
I partly solved the problem. The hardware setup is this:

Code:

(internet) ---- bridged modem/router (LAN port) ---- (LAN port) dd-wrt router


Note that the cable from the modem/router attaches to a LAN port on the dd-wrt router, not the WAN port! (otherwise the below does not work...)

On the dd-wrt router:

Configuration on the dd-wrt router

    Setup

      Basic setup

        WAN Connection Type
        Connection type: PPPoE
        Username: <username provided by ISP>
        Pwd: <password provided by ISP>

      Router IP

        Local IP Address: 192.168.1.1
        Subnet Mask: 255.255.255.0
        Gateway: 192.168.1.1
        Local DNS: 192.168.1.1

      Network Address Server Settings

        DHCP Type: DHCP Server
        Start IP Address: 192.168.1.2
        Static DNS 1: 8.8.8.8
        Static DNS 2: 8.8.4.4


    Wireless

      Basic Settings

        Physical Interface wl0
        Wireless Mode: AP
        Wireless Network Mode: Mixed
        Wireless Network Name (SSID): dd-wrt
        Wireless Channel: Auto
        Channel Width: 20 MHz
        Wireless SSID Broadcast: Enable
        Network Configuration: Bridged




The WAN IP of the dd-wrt router is an external IP, which shows that the bridging of the modem/router works, I think.

The problem: although devices can connect through wifi to the dd-wrt router, it seems that the LAN ports do not work: devices connected to it do not get an IP number. Anyone any ideas on how to solve this?

Any help very much appreciated...
rizla7
DD-WRT User


Joined: 11 May 2012
Posts: 293

PostPosted: Fri Jan 12, 2018 21:44    Post subject: Re: Partly solved => now LAN ports do not work (but wifi Reply with quote
jandot wrote:
(internet) ---- bridged modem/router (LAN port) ---- (LAN port) dd-wrt router


What? Use the WAN port...

It's because you LAN ports are most likely messed up in nvram values. In which case, one of the LAN ports is acting as a WAN port, the others won't work.

Do NOT set static DNS to google. Just leave it blank. It will use your ISP's DNS server (much faster). The router itself will act as a DNS forwarder. Add this line to services > dnsmasq options instead (although not strictly required):
Quote:
dhcp-option=br0,6,192.168.1.1

That sets your router as the DHCP server for all your LAN clients.

See these articles to fix your port/vlan configuration:

https://www.dd-wrt.com/wiki/index.php/Switched_Ports

https://www.dd-wrt.com/wiki/index.php/Default_Configuration_Overview

A bit dated, so you'll have to improvise. Btw, it's possible to brick the router if done incorrectly. Leave wireless GUI access enabled (and setup wireless), so you can fix it if need be, otherwise you're gonna regret it.
jandot
DD-WRT Novice


Joined: 09 Jan 2018
Posts: 4

PostPosted: Fri Jan 12, 2018 22:06    Post subject: Reply with quote
Thanks for the reply.

I actually just got it running again... Indeed, connecting to WAN instead of LAN was necessary. Then the system stated to act really weird: the URL 192.168.1.1 in my browser would either open the router's page, or the bridged modem/router. That didn't make sense at all to me...

One of the times that the admin page for the bridged modem/router I was able to switch of DHCP and wifi on that box. And lo and behold: I have access again...
Per Yngve Berg
DD-WRT Guru


Joined: 13 Aug 2013
Posts: 3655
Location: Akershus, Norway

PostPosted: Sat Jan 13, 2018 0:05    Post subject: Reply with quote
Change the LAN side of the router to 192.168.2.1 as it cannot be the same as the modem.
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