New device supported: Cudy LT400E v1

Hardware Questions and Recommendations
1

Hi everyone,

I'm happy to announce that I've recently added support for the Cudy LT400E v1 [1] router to OpenWrt. It is an MT7628-based device, it seems quite solid and stable. Based on my testing, all the functionalities work out of the box (booting, Ethernet, WiFi, 4G/LTE modem, LEDs, buttons). You can check the details on the device’s Wiki page [2].

Here are a couple of pictures of the device, and the board:

photo_2025-10-30_22-55-26
photo_2025-10-30_22-55-26300×225 9.14 KB
photo_2025-10-30_22-55-30
photo_2025-10-30_22-55-30300×225 11.1 KB
photo_2025-10-30_22-55-32
photo_2025-10-30_22-55-32300×225 14 KB

The stock firmware is an OpenWrt customized by Cudy. It looks very good, and has a lot of features (a nice GUI, advanced settings for network and firewall, VPN, WireGuard, IPv6, modem configuration, etc.). I think it’s a good product, so I thought it was worth the effort adding upstream support to it.

The stock firmware checks for a valid signature from the manufacturer when uploading a new image. Therefore, to flash upstream OpenWrt, an intermediate firmware image provided by Cudy that does not perform the signature check needs to be flashed first. Then, upstream OpenWrt can be flashed normally via sysupgrade. Cudy has a blog post about it [3], with links to a download folder.

I would like to thank the Cudy support team for their help. I contacted them to request this intermediate firmware image, and they promptly provided it to me. According to their message, they will be making it public soon, like they did for other devices already.

Cudy released the GPL sources (actually, the whole OpenWrt source code with all the modifications needed to support the device). My commit adding upstream support to the device is largely based on their code. I appreciate their commitment to the GPL and to the OpenWrt community.

Edit: Last, but not least, my commit is here [4]. I’ll be submitting a pull request soon. I just submitted a pull request [5].

Cheers!

[1] https://www.cudy.com/products/lt400e-1-0
[2] https://openwrt.org/toh/cudy/lt400e_v1
[3] https://www.cudy.com/blogs/faq/openwrt-software-download
[4] https://github.com/rogerpueyo/openwrt/tree/ramips-mt76x8-cudy-lt400e-v1_WiP
[5] https://github.com/openwrt/openwrt/pull/20660

3 Likes
2

The Flash ROM is 8MB only, that is a big problem. And no serial port.

3

There's a pre-populated serial header that's perfectly capable of being the serial port.

Hopefully this allows the LT300 to be added soon, which is the same chipset but a travel router.
Of course the LT300 3.0 has USB-C power and twice the flash at 16mb.

4

The LT300 looks very interesting, regarding price. Any idea, which modem (chip) built in ?

5

I'm hoping it's the ec200 same as the LT400.

At present I can't see anyone offering the lt300 3.0 model

6

While 8 MB is not much nowadays, I see ~1.5 MB free in /overlay with luci-ssl installed.
The device does have a serial port; you need to solder the headers first (reasonably easy) but also solder two tiny SMD resistors, which requires a professional soldering tool.

As I wrote above, in addition to the header, you need to solder tiny things. I'm documenting it in the wiki (it's the same for other Cudy devices).