Asus WiFi routers are great! … says the guy who owns two and just bought a third on Amazon yesterday. I’m not one to waste old hardware and I was thinking that I’d like to flash my old Asus routers with the DD-WRT firmware so I can transform them into WiFi-Repeaters!
Savvy readers will say, “But Rich, Asus already has AiMesh technology to do that. Why do you need DD-WRT?“
My response. “AiMesh only works on recent Asus models, it doesn’t work on my N66R for instance. DD-WRT works perfectly fine and breaths new life into that obsolete model”.
So now that we have established why we’d want to do this, let’s roll up our sleeves and get to flashing….
Step 1: Do Your Research
Flashing the firmware of a WiFi router is not trivial; first and foremost you need to visit dd-wrt.com and see if your router is supported. Search the router database for your manufacturer model (e.g. asus). Some WiFi routers have multiple (confusing) retail names for the same hardware and some retail names have multiple different hardware revisions! Check the serial number and the hardware revision indication on the label of your WiFi routers, my RT-N66U is hardware revision B1. Checking the router database, my hardware revision from 2011 is supported and a fresh firmware file as of 2019!
Step 2: Download the firmware file to your desktop or laptop
You need to prepare by saving a copy of the .trx firmware file to your local computer (desktop or laptop) that you will use to flash the WiFi router. The file is not very large; about 22 Mb in this example. Please note there are various build numbers in the pulldown combo box. I chose the latest file. You can download multiple .trx files from different builds, but make sure to take notes of which file is which so you aren’t confused later.
Step 3: Read the flashing instructions at least twice
Remember the old Carpenters saying, “Measure twice, cut once”. Flashing the firmware of a router is a bit like baking a cake; you need to follow a list of instructions precisely or the end product will not be good (edible?). In my instance, the first line of the instructions says “Note that the two existing hardware revisions, “A1” and “B1”, of this router are significantly different. This page is about revision “A1”, typically referred to as RT-AC66U, without the revision. For information about the “B1” revision, see Asus_RT-AC66U_B1.” Now, I follow the new link to updated instructions and I see hardware revision A1 and B1 instructions are radically different. I notice the next block of bolded text, “it is recommended that you flash an RT-AC68U build. RT-AC66U builds are optimized for revision A1 and will not work with this router.” Wow, I was really lucky there. I could have ruined this router by flashing the wrong firmware that I downloaded in the previous step. I follow the updated instructions to download the AC68U firmware file.
Step 4: Connect your computer to the Wifi router to flash the firmware
You will most likely do this step several times before you get it right. Follow the linked instructions, steps 1-14. Make sure you are not rushed and I always like to have a bit of music playing to help keep stress levels down. Steps 1-4 are simple, please remember to disconnect from any other WiFi routers and connect a cat6 cable from your computer to the router you want to flash. Make sure you connect to the LAN port, not the WAN port. Steps 5-9 explain how to put your Asus router in “rescue mode” to enable the flashing of firmware. While there is a firmware flash mode in the typical Asus menu, it will not allow you to flash a 3rd party firmware like dd-wrt. If you followed the steps correctly, your power LED will be flashing slowly and 192.168.1.1 will show a simple webpage entitled ASUSTek – CFE miniWeb Server. Step 10 tells you to “Restoredefault NVRAM values” and step 11 prompts you to browse for the .trx firmware file on your computer and click upload. It will take maybe a minute or two to transfer the file at which point the webpage will say flashing the firmware, please wait a few moments. I asked how long are a few moments? It says the router will reboot when complete. Be patient, wait at least 15-20 min to let the firmware file flash and you’ll know when it’s done when the router reboots and the power light goes solid (no blink). Now, I used the AC68U firmware file like the instructions warned me to do but that didn’t work (I tried 3 times). On a lark I used the n66u firmware .trx file I originally downloaded and it worked like a champ! go figure….
Step 5: Configure your newly flashed DD-WRT router
After the router reboots from the flash, connect via your PC which is still connected via the CAT6 cable to http://192.168.1.1 which is the default IP address for your WiFi router. You might also see a WiFi SSID of dd-wrt on your network. When you first connect you will be prompted to choose a login name and password for your router. Make sure you don’t forget these as they are the admin credentials. For me, this router is a second router on the network (i.e. it’s not my primary router). If I was try and connect it to my main network, I would get an IP address conflict for 192.168.1.1 which is the actual IP address of my primary router. In the setup tab in the Network Setup section I changed the routers IP address to 192.168.1.2 and set the subnet mask to 255.255.255.0. I set the gateway to 192.168.1.1 and I set my DNS to 192.168.1.133 (which is my pihole server << more on that in another blog post). I disabled the WAN connection type and gave my router the name lung (you see my primary router is always named heart). I hit save and apply settings and I believe the router restarted. I can now plug this router via CAT6 cable into my primary router to check that they happily co-exist.
Step 6: Setup the WiFi repeater
AiMesh and DD-WRT WiFi repeater mode essentially allow you to extend your WiFi coverage and you can leverage one band (2.4 GHz for example) to do the bridge and rebroadcast on another band. There are so many combinations here I’m not entirely sure which one is best. I stumbled upon a great Youtube channel called Behfor that walks you thru the what’s and the why’s of your WiFi router and setting up the repeater. Look for the video entitled Dual Band DD-WRT Repeater Bridge. I’m still playing around with this part 😉 Let me know if this was helpful or if you are using WiFi Repeater.