New Install on WNDR4700/WNDR4720 with OpenWrt 18.06.2

I had earlier written about LEDE 17x install on WNDR4700 here LEDE 17x install on WNDR4700/WNDR4720

Recently, I decided to add a new 4TB drive I had spare with me and while, I was at it might as well move up to 18.06.2 version. I have to say that this version of software install is not only much more polished, it feels like its even faster on the same hardware without any overclocking.

There were only few tweaks I made:

  1. For the multi-wan set up, instead of using wan2, I decided to use wanb. Its possible to delete wanb and in its place add wan2 using luci but I was just feeling lazy.

  2. I added kmod drivers for UAS access to the newer usb drives. The internal drive of 4tb worked like charm. I used gdisk to make partition.

I also had to manually install uPD72020x firmware to get usb3 working.

I did extensively tested to see if the machine will recognize the sdcard, but I was not successful. I would love to try that out and make that work not because I need it but because engineers often do!! And, I promise that if it worked, I will come here and post my recipe for making that work.

Also, I do find that since I have the fan detached, it does get run little hot. I wish I knew or had a recipe to control the fan (switch on only if it exceeded 45 Celsius) and would love to lay my hands on the recipe.

If you guys have any question, do let me know and I can share my experience. And, if you have any pointers to (1) SD Card and (2) fan control, please do let me know and I will appreciate it.


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How about a relay controlled by a thermistor then?

Hi Trendy: Thermistor is a cool idea (pun!! intended) but I am not skilled to add electronics parts. I would think that the electronics and linux utils can handle this easily...But I may be wrong. I recall that Chunkeey had earlier alluded to that.

Any pointers on the Thermistor specs or URL? Thanks.

Unless your router has I2C pins available to you, I'd suggest a separate MPU to control the fan. Lots of sensors out there and most any Arduino-like device should be more than powerful enough.

Some ideas at

If I were doing it, I'd go with something like an MCP9808 (because it is I2C and doesn't require external components, I have a few on my bench, and they're reasonably inexpensive) and a MOSFET to switch the fan.

Check the voltages you have available on the board before you decide on a 5 V or a 3.3 V MPU, or run it off USB. I personally have grown tired of the "classic" AVR chips and am using ARM Cortex-series MPUs, but for this, even the tiniest of AVR units (such as an ATMega32U4 pro micro) should be sufficient. Running it off USB means you can amuse yourself by controlling / reading it from the router's serial.

Rough US$ prices (Adafruit, as one supplier):

MCP9808 -- $5
MOSFET -- $2
Trinket M0 -- $9

Adafruit is also carried by Mouser (and likely Digikey) in the US as well.

There are also STM boards like the "blue pill" for about $3 off eBay and similar channels that would be more than sufficient.

Edit: suggests that there is a "Lantiq CPU temperature sensor" available.

Now you'd only need a way to control the fan, a single GPIO that was accessible could do it with a MOSFET. You could perhaps even use an LED line, which becomes your "Fan On" LED as well.


Jeff: Thanks for getting me to think and I have been now studying Adafruit slowly... along with esp01/esp12/esp32.

Which made me decide to wndr4700 again to use as a server after EXroot. It has a big processor and not too bad RAM.
I installed MSQTT and Domoticz and even though it is not leaded the web interface responds very quickly.
May be there is salvation for an old man like me!!!

Thanks again.


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Hi Anil,
you can use this solution for wndr4700:

echo "disabled" > /sys/class/thermal/thermal_zone0/mode
echo "1" > /sys/class/hwmon/hwmon1/pwm1_mode
echo "0" > /sys/class/hwmon/hwmon1/pwm1

and write some script like in post Automatic fan control - Linksys WRT1900AC

UPD: cheched fan-control on OpenWrt 19.07.4

Oh. WOW, Thanks so much. I will redeploy that router to test this out. Also flash it with new love that have been released since. Be well and stay safe.