TP-Link Archer C50 (EU) V6.0 - 5 GHz interface not present

[Jack2]

I'll share my own experience. Starting with a stock firmware on the Archer C50 v6 EU, I tried installing one of the snapshots through TP-Link's online firmware upload interface. The first time I did it, nothing changed. The second time, I believe I got disconnected (I did both through Wi-Fi like an idiot). Well, that lead to a brick. Maybe it is because I didn't follow these instructions here:

TP-Link Archer C50 (EU) V6.0 - 5 GHz interface not present

Hi xristos, did you follow the instruction that explains prepending the bootloader to the sysupgrade image? According to the instructions if there is no bootloader prepended, it will cause a brick. It seems good news that the router is still attempting a tftp connection. Which model are you using? What tp_recovery.bin file are you using?

I spent the whole night trying to fix it, fearing I had bricked the boot-loader and that I'd have to get a £50 JTAG cable or something. I had some spare Raspberry Pis and I set up a TFTP server on one, using tftp-hpa and these instructions.

I had set the IP address to 192.168.0.66/24, connected the router and the Pi through LAN1 using a CCA Ethernet patch cable, and monitoring using tcpdump -ni eth0, I was seeing who-has requests for 192.168.0.66 everytime I did the reset process (hold down the reset button, then power on and keep holding it), though that may just be some DHCP/ARP protocol thing. I couldn't see any kind of request specifically for tftp-hpa.service, so I feared TFTP recovery was out of the window.

I then tried it the next day on a Windows 10 machine using Ttfpd64, and it worked perfectly. So it's not a boot-loader brick! I had flashed the tp_recovery.bin that was for v4:

Restoring Stock Firmware for Archer C50 V4

It finally worked! I did it by doing all the steps using HxD editor and not doing any of them using Linux or dd commands. I selected then removed the first 0x200 bytes, inserted 0x30000 bytes at the beginning containing zeros, and selected then deleted 0x30000 bytes of FFs at the end of the file and flashed it using TFTP. Thanks for your advice on using this application, I hope we can install a stable version of OpenWRT on our devices soon! I have uploaded the edited stock file for the above …

and I'm back to a nearly-perfect point. The problem is precisely that the firmware is for v4, and that's now what my router thinks it is. It won't let me flash the v6 official image, like he describes, instead giving me an error code 4503 (The uploaded file was not accepted by the device).

Apparently he had success using TFTP, so I set that up again, using the MediaFire link he created here:

TP-Link Archer C50 (EU) V6.0 - 5 GHz interface not present

[Untitled] but when i try to flash though 192.168.0.1 i get Error code: 4503 The uploaded file was not accepted by the device. i manage to flash it through tftp though and it works so far this tp_recovery is ready to use with tftp (for our windows folks)

and it does flash over. Only now, the device is not discoverable or reachable. Suspecting maybe he created an OpenWRT image, I tested ssh root@192.168.1.1, which doesn't work. I tested reaching the TP-Link portal, 192.168.0.1 and the one I guess OpenWRT uses, 192.168.1.1. Neither work. @xristos, if you have anymore information on how you achieved this, it'd be much appreciated.

So I've re-flashed the v4 firmware. I'm not extremely fussed about it, but I would like if anyone has any guidance for bringing it back to the official v6 firmware, which I can stay at until v6 support is proper. Maybe I'll get my own feet wet in the semester holidays.

I'm assuming, reading about the talk around the split-uboot design and that my TFTP recovery worked, that my factory-uboot (at 0x00000000) is untouched, and that a perfect official reinstall is still possible. Hopefully I haven't lost any calibration data or functionality permanently.