Setting up an OpenWRT router

Instructions are here http://wiki.openwrt.org/toh/tp-link/tl-mr3020?s[]=mr3020

This page also contains the downloadable firmware. Make sure you download the right version! You will need to check the hardware version; inside the casing, behind where the battery sits, is a sticker that has the make and model, including the all-important Hardware Version (mine was 1.9). If you use the wrong firmware, you might get lucky and the router will refuse to update, but if you succeed in installing the wrong firmware you may very well irrevocably break the router.

Unbox the TP-Link TL-MR3020. Out of the box it probably comes with the mode switch set to 3G/4G (as opposed to WISP or AP); just leave it as is.

Turn it on. A wifi access point called something like TP-LINK_POCKET_3020_XXXXXX. Connect to it using the wireless; there is an 8 digit numeric password labelled 'PIN' on the bottom right part of the sticker on the side of the router.

Open a browser, and navigate to: 192.168.0.254

This should bring up a username/password popup, both the username and password are "admin". There are 2-3 configuration screens; just accept the defaults.

Now you should be in the router's configuration page; at the bottom of the left-most pane is a "system tools" link, under which you'll find the "firmware upgrade" link.

Hit the upgrade button, and navigate to the file that that you downloaded (probably openwrt-ar71xx-generic-tl-mr3020-v1-squashfs-factory.bin)

Wait for the progress bar to complete TWICE (once for the installation, once for reboot).

Now plug it into the Ethernet, and go to 192.168.1.1 (not the original 192.168.0.254).

Log in with username root and no password (probably just push the login button, as the default username and blank password are likely pre-filled).

Now you're in the dashboard, go to the System tab and Administration page in the drop-down, and set a password. I used 'plumpynut'.

####Then set up a wireless

Navigate to Network, Wifi. In 'Wireless Overview' there will be one interface named 'OpenWrt'. Click to 'Edit' this, which opens up a configuration dialog. First click 'Enable' to enable the wireless network. Then, if you care what channel you're on (for example if you have other networks in the same airspace) set the channel to not conflict with the others. In the 'Interface Configuration', replace the ESSID with "buendia". Next click on the 'Wireless Security' tab, select WPA-PSK encryption in the dropdown box, and add Key 'plumpynut' for the wifi password.

####Configure router as a Dumb AP

Go to Network → Interfaces and select the Lan interface. Click to 'Edit'.

Set an IP next to your main router on the field "IPv4 address". (If your main router has IP 192.168.1.1 set 192.168.1.2)

Then scroll down and select the checkbox "Ignore interface: Disable DHCP for this interface."

Click the Save and Apply button. Hard-Restart your router if you're not able to connect anymore.