Note: TP-Link also markets a very different router under the same name.
Even though it is marketed as a "3G travel router", the TL-WR720N does not include a 3G modem. It simply means that the OEM firmware and GUI support a certain range of USB 3G modems. OpenWRT supports USB 3G modems, too. The router is powered through either a AC source (100-240V, Chinese-style foldable plug, i.e. two prongs without hole), or a micro-USB socket stub (5V).
The domestic Chinese/Asian versions and those for the European and American markets differ significantly. Only the rectangular version available from China has been tested, so far.
|Model Version||Launch Date||OpenWrt Version Supported||Model Specific Notes|
|v3.0||N/A||14.07||Chinese version (rectangular)|
|v4.0||N/A||No direct support; firmwares for v3.0 work.||Chinese version (rectangular)|
|Atheros AR9331@400MHz||32MiB||4MiB||2 x 100MBit||1 x 2.0||Yes||Unlikely|
As from 28 April 2013, support for the TL-WR720N is present in the Trunk version of OpenWrt, see this thread on the forum for further reference.
The hardware of v4.0 is almost the same as v3.0 so firmwares for v3.0 just work. The version number in images for v4.0 is 0x07200104 (0x07200103 for v3.0).
this is based on a tutorial found here.
At baidu you can download the needed files (password is u2e9)
Step 1 is to enable uboot-flashing:
wr720nv4/wr720nv4解锁ubootopenwrt固件.bin (3.8M 20141030 11:09 MD5sum 321248fc3d9121b261ffc6f35b60bbde) and flash it from the original web interface (192.168.1.253)
You can find the firmware update in the webinterface the following way:
"System" is the first entry under the semi-readable (*DNS*) on the left side pane.
Then the third entry is firmware update. If in doubt, use google translate.
Afterwards a bb openwrt-image with write enabled mtd uboot partition is flashed.
Step 2 is to get the pepe2k uboot:
get the files from the wr720nv4\*\*\*uboot folder
copy them to the wr720nv4
$ scp flash.sh wr720n-v4-uboot-pepe.bin firstname.lastname@example.org:/tmp $ ssh email@example.com root@OpenWrt:/tmp# sh flash.sh wr720n-v4-uboot-pepe.bin 9acf3d80cdcf70375618d900ab355cdc wr720n-v4-uboot-pepe.bin md5sum : 9acf3d80cdcf70375618d900ab355cdc wr720n-v4-uboot-pepe.bin md5sum check pass 0+1 records in 0+1 records out 64512+0 records in 64512+0 records out Backuping to uboot_backup.bin Backup some config first,just like MAC address ... 1024+0 records in 1024+0 records out Flashing Sync Finishedpower it down, power it up and immediatly after powering up, press the reset button until the led flashed three times. you should be able to access the uboot webinterface at 192.168.1.1
OpenWrt-ImageBuilder-ar71xx_generic-for-linux-x86_64$ nice -n 19 make image PROFILE=TLWR720 PACKAGES="openvpn-polarssl luci -ip6tables -kmod-ip6tables -kmod-ipv6 -ppp -ppp-mod-pppoe -odhcp6c -luci-proto-ipv6 -luci-proto-ppp" OpenWrt-ImageBuilder-ar71xx_generic-for-linux-x86_64$ scp bin/ar71xx/openwrt-ar71xx-generic-tl-wr720n-v3-squashfs-sysupgrade.bin firstname.lastname@example.org:/tmp/The ImageBuilder builds for the v3 but still the image works fine.
$ ssh email@example.com root@OpenWrt:~# sysupgrade -v /tmp/openwrt-ar71xx-generic-tl-wr720n-v3-squashfs-sysupgrade.bin Invalid image, hardware ID mismatch, hw:07200104 image:07200103. Image check 'platform_check_image' failed. root@OpenWrt:~# sysupgrade -F -v /tmp/openwrt-ar71xx-generic-tl-wr720n-v3-squashfs-sysupgrade.bin Invalid image, hardware ID mismatch, hw:07200104 image:07200103. Image check 'platform_check_image' failed but --force given - will update anyway! .... Performing system upgrade... Unlocking firmware ... Writing from <stdin> to firmware ... Appending jffs2 data from /tmp/sysupgrade.tgz to firmware...TRX header not found Error fixing up TRX header Upgrade completed Rebooting system...
Enjoy your new openwrt on 192.168.1.1
It appears the hardware switch must be set to "3G" to make the USB port work. Otherwise the port has power output but devices connected can't be detected by OpenWrt.
Note that the mount_root command will not work. (You can use the netcat method to install a fresh copy of the system if necessary.)
TP_IN is RX, TP_OUT is TX, and you may solder a ground above R323. The connection speed is 115200, N, 8, 1.
user: root pass: 5up
To access the u-boot bootloader, enter 'tpl'+<enter> when the 'Autoboot in 1 sec' message is displayed.
Forum member pepe2k made a modification of U-Boot 1.1.4 for Qualcomm Atheros SoCs based devices (the project is still being developed, so new devices and SoCs will be supported in the future). Up to date information, binary images and sources can be found on official GitHub repository.
This modification started from wr703n-uboot-with-web-failsafe project, but supports more devices, all modern web browsers, has a lot of improvements and other modifications (like U-Boot NetConsole, custom commands, overclocking possibilities etc.).