How to Flash TP-Link TL-WR740N

TP-Link’s WR740N is a very lowcost wireless router capable of running OpenWRT. I bought it for 12 LVL (~23 USD / 18 EUR) and it had the v4.2 of WR740N and thanks to good guys at OpenWRT I was able to replace my buggy original firmware with solid firmware that was capable of doing what I need, specifically, connect as a client to a existing wifi network.

Hardware highlights

• CPU – Atheros A7240 @ 400 MHz
• RAM – 32 MB
• Flash – 4 MB
• WiFi – 802.11 b/g/n 150 Mbps
• Network – 4 x 10/100 Mbps Ethernet

Here are some images of WR704N. I already played a bit with the LEDs, that’s why I have WLAN and WAN LEDs working :)

Original firmware doesn’t supports connecting as a wireless client and has a buggy implementation of WDS, anyway, here’s how to flash a WR740N with OpenWRT from trunk (currently r30479). Fortunately there’s even a wiki statement that provides us with solid ground to work on: „V4.2 and V4.3 work without apparent problems from trunk r29631 onward”.

Prerequisites

• PuTTY – a SSH, Telnet and Rlogin client (download here)
• Original TL-WR740N firmware – (download here) for recovery purposes :)
• Trunk OpenWRT version for WR740N (download here)

Installation

It seems that the only difference between WR740N and WR740ND is that the later has a detachable antenna so it is safe to follow it’s tutorial. The manual at openwrt.org says that some of the devices have a protection for uploading unsuitable firmware, but this wasn’t the case. I think it was more aimed towards the D version. The trunk WR740N image can be flashed trough the stock TP-Link web interface.

• Browse to your router (default http://192.168.1.1/ )
• Login with your credentials (default user name: admin, password: admin)
• On the left side navigation go to System tools then to Factory defaults and click restore
• After router has rebooted navigate to Firmware upgrade
• Upload previously downloaded *-factory.bin file to router
• Click on Upgrade button and wait for it to reboot
• Wait about a minute or so (watch the sys led activity)

Configuration

Now it’s time to open previously downloaded PuTTY executable and setup a password for root account.

• Open PuTTY and type 192.168.1.1 in the Host name field
• select „Telnet” as connection type and click open
• After the OpenWRT banner/greeting type: „passwd root” without the quotes and enter your password twice
• Once password has been setup Telnet is no longer avaiable, use SSH instead

And that finishes the installation of OpenWRT on TL-WR740N. For basic configuration of your device head to OpenWRT wiki. And again thanks to the good guys at OpenWRT for making this happen!