Test your router: If your router is properly connected to the internet you should get something like the below lines:

Please note: The products of TP-Link partly contain software code developed by third parties, including software code subject to the GNU General Public Licence (“GPL“), Version 1/Version 2/Version 3 or GNU Lesser General Public License ("LGPL"). You may use the respective software condition to following the GPL licence terms. Notice the amount of distortion outside of the 20MHz signal at 1800 compared to 1200 or 900. It is hard to say how much of this distortion is also available in the 20MHz signal, my guess is at least as much. This cripples the signal, making a greater txpower probably a worse signal with less speed than one without the distortion.

Firmware

DONT DO ANYTHING. Just wait and router reboot itself. wait few minutes and you will able to reach Luci via 192.168.1.1. Microsoft® Windows® 98SE, NT, 2000, XP, Vista™ of Windows 7, 10, MAC® OS, NetWare®, UNIX® of Linux. Please note: The products of TP-LINK partly contain software code developed by third parties, including software code subject to the GNU General Public Licence (“GPL“), Version 1/Version 2/Version 3 or GNU Lesser General Public License ("LGPL"). You may use the respective software condition to following the GPL licence terms. The txpower sweetspot is therefor estimated to be 1000-1200. This would equal a signal strength of 2-4dBm (1.5-2.5mW). To max that up to the common legal maximum of 100mW ERP you'll need an 18-21dBi antenna. You'll be much better of with a clean signal and a high gain antenna than attempting to crank up the signal strength to a level where it only cripple the signal with distortion. If you are using a Linux or Mac system, the easiest way to connect to the serial console would be the screen command. It comes pre-installed on OS X, but must usually be installed on Linux systems. When installed, just type in a terminal:

Please verify the hardware version of your device for the firmware version. Wrong firmware upgrade may damage your device and void the warranty. ( Normally Vx.0=Vx.6/Vx.8 (eg:V1.0=V1.6/V1.8); Vx.x0=Vx.x6/Vx.x8 (eg:V1.20=V1.26/V1.28) To install OpenWrt from the U-Boot console, you need to install a TFTP server on your computer ( tftp-hpa is recommended). Downgraded wrong image ( jff2 instead of squashfs ) cause cant get ip or connect to luci. Failsafe mode still working but firstboot command wont work because it is already on working. You can upload correct firmware and write it with mtd command but failsafe mode can't connect internet. You need to local tftp server to get firmware. It's recommended that users stop all Internet applications on the computer, or simply disconnect Internet line from the device before the upgrade.Kernel command line: console=ttyS0,115200 root=31:02 rootfstype=squashfs init=/sbin/init mtdparts=ar7240-nor0:128k(u-boot),1024k(kernel),2816(rootfs),64k(config),64k(ART) mem=32M A firmware update can resolve issues that the previous firmware version may have and improve its current performance. To Upgrade

To get a reliable serial connection, you might have to connect a 10k pullup resistor between TX and VCC. This is because the TX pin is connected to a voltage divider (2×5.6k) and a capacitor is put between the real pin and the TX connector. Some serial adaptors might work without the pullup resistor (confirmed for one ST3232-based adaptor), but others definitely require it (confirmed for a FTDI FT232RL-based model). Linux version 2.6.31--LSDK-9.2.0.312 (root@bogon) (gcc version 4.3.3 (GCC) ) #185 Fri Oct 21 16:26:50 CST 2011Is is very evident that the greater txpower, the greater amount of noise and distortion in the signal. The signal is very clear around txpower 800, while rather terrible when set to 1800 and more. To avoid wireless disconnect issue during firmware upgrade process, it's recommended to upload firmware with wired connection unless there is no LAN/Ethernet port on your TP-Link device.

The difference is rather small and probably due to soldering and possibly quality of analogue components on the PCB. Noise level is rather constant between the two tests though.

Emulators

Some official firmware of TP-Link products can be replaced by the third party firmware such as DD-WRT. TP-Link is not obligated to provide any maintenance or support for it, and does not guarantee the performance and stability of third party firmware. Damage to the product as a result of using third party firmware will void the product's warranty. Open Source Code For Programmers (GPL) How to solve the compatibility problem between your 3G modem and TP-Link 3G router 06-10-2021 109810 Microsoft® Windows® 98SE, NT, 2000, XP, Vista™ or Windows 7, 10, MAC® OS, NetWare®, UNIX® or Linux.