TP-Link WR841n ver 7.2 serial console RX help

Installing and Using OpenWrt
1

Hi All,

I have an old TP-Link WR841n which I somehow soft-bricked.
It boots but does not connect. This is the end of the console log:

[ 0.000000] bootconsole [early0] enabled 
[ 0.000000] CPU0 revision is: 00019374 (MIPS 24Kc) 
[ 0.000000] SoC: Atheros AR7241 rev 1
[ 0.000000] Determined physical RAM map: 
[ 0.000000] memory: 02000000 @ 00000000 (usable)
...
...
...
+?rª????] random: ubusd: uninitialized urandom read (4 bytes read) +?r??????] random: ubusd: uninitialized urandom read (4 bytes read) +?r??????] random: ubusd: uninitialized urandom read (4 bytes read) +?r??????] procd: - init - ???͕ press Enter to activate this console.

Looks like this v7.2 does not have TFTP on reset, so I had to connect to it on serial console. I can read the console output, but looks like RX does not work, it does not react to anything so I cannot stop the boot.

I've read at few places that TP-Link blocks the serial RX but it is unclear how to solve it and I found different suggestions.

This is a photo of my board (apologies, couldn't attach it):

I'm not sure if I need to remove R612 or leave in place and bridge R614?
My board on the photo is:

Tx
Rx
GND
Vcc

The R612 is a 10kOhm resistor. The closer side of it beeps to the Rx pin.
The other side of it beeps to GND, so I assume I should remove R612?

Thank you very much!

2

Woo-hoo!! I managed to interrupt the boot. How it was solved, no idea though. It was not reacting to typing "tpl", but after some trials got to the menu :slight_smile:

3

Glad you solved your issue.

That said, the device is not safe to use anymore because it cannot run an up-to-date version of OpenWrt. As a 4/32 device, OpenWrt support ended with ~18.06 which has been EOL and unsupported (and critically unpatched) for well over half a decade already.

With that in mind, you should be looking for new hardware that can run 25.12+.

4

Thank you Sir :slight_smile: I managed to reinstall OpenWrt 15 using TFTP + serial. It is not for normal use, I'm just using this router for testing and building custom OpenWrt for learning. I made a mistake years ago, put it in the drawer and now managed to restore it.

5

The changes over the last decade (from 15.05 --> 25.12) are massive. Learning on such an old version isn't really all that useful, IMO.