Can't access my OpenWRT (DEco M4r v4 )

Installing and Using OpenWrt
1

I have a DEco M4r v4 which I flashed with OpenWRT.

I installed rampips-mt7621-tplink_deco-m4r-v4-squashfs-factory.bin on it (I believe - there were 3 version I downloaded and I think I installed that one). I was adjusting some of the interfaces and I can't get access to it any longer. I tried to go and use the factory reset page but I haven't been able to have any luck with that. It doesn't really have a button - but I've tried pressing the reset button during that window. I've tried using wireshark and filtering for UDP 4919 when attached to eth0 when the green light is flashing quickly - but nothing appears.

Do you have any suggestions how I can regain access to it?

2

Have you tried the openwrt failsafe mode?

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3

Which I believe is to press a button (which I don't really have) within the 2 seconds of 5 per second flashing. Like I said, I pressed the factory reset button that window but it never changed to 10 per second. Just proceded to 2.5 per sec (which I believe is standard boot).

I've also held the reset button for 20 seconds but I see no change in the leds so I assume nothing has happened. I've then tried to set my ethernet to 192.168.1.100 to communicate with it - but nothing appears on the webpage.

4

Press and release the button continuously immediately after applying power. You’ll be looking for a led to begin flashing rapidly. If that doesn’t work you will probably need a serial console to figure out what is happening.

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5

When I do it before it powers up, it stay yellow flashing (slowly). When I let it got to the green flashing it just proceeds to the slow and the solid. I've waited 5 minutes to see if the yellow flashing changes. But I don't see anything differently - and on reboot it returns to the same process. (and displays its original assigned ip address in the arp broadcast (seen from Wireshark)

What does a serial console look like? I'm just looking to somehow do a factory reset and undo to the bridge I put in.

6

If you succeed to enter the failsafe mode, there is no webGUI, just the SSH console at 192.168.1.1

(Edit: sorry, I originally thought that you thought the router to have 192.168.1.100, but apparently not.)

7

Haven't seen the UDP 4919 package though. I've also tried doing TCPdump and hitting keys but that doesn't have an impact either.

Does that mean I've installed the wrong version?

8

No idea.

But there seems to a hint in the device support creation commit, that the device has a recovery in u-boot bootloader.
That might be your best bet if reset or failsafe does not work.

Flash the *-factory.bin image in the U-Boot recovery webserver.
You can trigger this webserver by holding the reset button until the LED
flashes yellow,

(I have never used tp-link devices, so no knowledge about tp-link recovery details, IP address etc)

9

That's how I originally loaded the software into it. It loaded and created a webpage at 192.168.1.1 - which I was able to upload. However now that I have openwrt loaded - it doesn't seem to exist in there any longer. The lights flash but nothing seems to exist there. Probably that area got overwritten with openwrt.

The device definitely isn't bricked. I can see the arp requests from it when it enters openwrt. It just refuses the tcp when I communicate because of how I confirgure the interfaces.

Is there another way to somehow reflash it?

10

Make sure there are no other connections whatsoever except for an ethernet connection directly between the deco unit and your computer -- no other ethernet cables should be connected to either device. Also disable wifi on your computer (if applicable).

Then, set your computer's ethernet connection to get an address via DHCP and then let us know if your computer successfully gets a DHCP lease. If it does, please provide the address here.

11

I've only been testing with the one cable.

I just get the preferred ip4 and ip6 address when I connect to the router. Using wireshark I can see the Arp broadcast from the TP_link ("Who has 192.168.2.1? Tell 192.168.2.6") in wireshark. There just is no UDP traffic on I do see some DHCP Discover requests from it on the second eth port but it doesn't get assigned an address.

12

Does your computer get a DHCP lease? If so, what is it?

If not, have you tried the other physical por(s) on the device?

13

Not from this router. I have other routers in my house. This router can not respond correctly because of how I bridged one of the interfaces. There is only 2 ports and I have tried every configuration - and tracked with wireshark. I've attached both to DHCP servers. This port can do some TCP negotiation but when I it will ultimately reject the connection. (eg. when a 192.168.2.108 talks with it as I mentioned it is sending its ARP protocols.)

I will say wireshark is absolutely amazing at inspection. Never used it for this purpose before but it is very incightful. For example it shows that the failsafe protocol on udp isn't being sent. Which probably means I installed the wrong version.

Don't know if this helps but when 192.168.2.108 talks with 192.168.2.6 via TCP it states [TCP Port number reused] 9722 ->80 [Syn] Seq=0 Win=6420 Len-0 MSS=1460 WS=256 Sack_perm

14

Oh... so you changed the configuration of the device? It sounded like you had just flashed OpenWrt and then lost access, but maybe that's not the case?

15

Yes. I was trying to setup a Vlan - and then screwed it up by adding an interface. Completely my fault.

OpenWRT was working fine. And was really impressed with it (have used dd-wrt from years back and wow its soo much better).

16

Well, the best way to fix this is to use failsafe. It’s probably worth trying that again.

17

But I can't flash it and there is no post UDP 4919 by 192.168.1.1. I must not have installed the version with fs. The failsafe doesn't work. The buttons do not respond and I've verified this multiple times with Wireshark attaching the ethernet to all ports.

18

Like I said above, if failsafe does not work for you, your best bet is the u-boot recovery by the OEM bootloader. OpenWrt should have not touched it any way, so it should still work. But it may require a specific IP address on PC etc. (like many tp-link routers do).

19

If you setup vlans have you tried setting your pc straight to that vlan and connecting directly?

20

There’s a vlan option in the adapter settings on windows 10 and 11