The DSL-2730U was a common DSL modem-router in the heydays of DSL in India, but now that I have moved on to an optical link, I wanted to re-purpose the modem as a router.

Warning: You will no longer have DSL! You might end up with a brick!! There is no wifi yet!!!

The good news is that the modem has a recovery mode which should help recover from most issues. Turn off the modem. Use a pen to hold down the reset button and turn it back on. The power LED should now turn red. You are now in recovery mode.

So these are the steps (roughly) by which I managed to install openwrt on DLink DSL-2730U C1.

1. Figure out the platform and wifi

Version being C1, SoC is BCM6328 and wifi is BCM4313. ROM is 8MB and RAM 32MB. There is no official OpenWRT support for our model. Too bad.

2. Get the ROM

Go to the OpenWRT site, downloads, then look for the generic brcm6328 image. The link below is only a suggestion, perhaps a newer version will work as well.

https://downloads.openwrt.org/releases/17.01.4/targets/brcm63xx/generic/

You need the 8MB generic image, it should be named something like:

96328avng-generic-squashfs-cfe-8M.bin

3. Flash the ROM

Enter recovery mode (hold reset down when you turn it on).

Connect to the computer with an ethernet cable and go to the recovery address at 192.168.1.1.

A simple page loads. Follow instructions to select and flash the previously downloaded rom. This will take a minute. Modem will eventually reboot and you can log into OpenWRT at 192.168.1.1.

4. Set up routing

a. I set up ethernet port 1 as the wan port. Add a new VLAN in Network>Switch. Turn off port 1 in the existing VLAN and set it to ‘untagged’ in the new one. Set the cpu to tagged in both.

b. Add a new interface in Network>Interfaces. Select the VLAN you just created and select the WAN firewall zone for it. Set up the WAN using the info your ISP gave you, in my case a static ip address.

Now you can connect the device to your regular modem as a router.

Now for the bonus section.

5. Try installing WiFi drivers (but probably a waste of time)

To refresh package list and install the brcmsmac wifi driver:

opkg update
opkg install kmod-brcmsmac
rmmod brcmsmac
modprobe brcmsmac
Now to refresh the configuration files:
rm -f /etc/config/wireless
wifi config
cat /etc/config/wireless

Hopefully you just saw a wireless interface listed. Now you might want to install WPA security:

opkg install wpad-mini

For me the wifi module (BCM4313) is detected and configurable but fails to start up due to some issue with suspend. YMMV.