@David-TP 

What's the point? I might not be a network engineer, but I definitely know my way around network settings in xDSL routers. Besides, you cannot define a DHCP range that is on a different subnet from the router's IP.

The software is buggy, but I cannot help you on which part of it since the only good security I see in this router is the lock of the JS files.

Since I mentioned security, why on earth do you have telnet enabled? But this is for another post.

To give you some more information in case you can reproduce it in your labs.

1. Configure router via the web-ui and quick setup.
2. Reboot the router
3. Change the LAN settings so as the internal IP is different from the default one (let's say 10.1.1.254).
4. Define a DHCP range of 10.1.1.220 - 10.1.1.252
5. Save some static DHCP definitions
6. Save the configuration (this will be OK)
7. Wait until the router is up again
   1. Set a password for the Guest Network and save it. This will result to a loss of the Internet connection. Upon login to the provider, the router's IP is changed to the default. In 50% of the cases (and I tried a lot of them), guest network password was not saved.
   2. Set a static IP on your xDSL settings. This will result to a loss of Internet connection (for absolutely NO reason) and upon router's reboot, the IP is changed to the default. Static IP is saved
8. Any attempt to change router's IP and DHCP will result to reboot and of course the IP (and the DHCP range) will be restored to the default one! 

The only viable workaround I find is this:

• Wait until your DSL connection is up. Do all the changes you want on the WIFI network. Save them, logout and re-login. Then backup the configuration.
• Wait until your DSL connection is up. Do other changes in your configuration (eg change the DHCP range). Save them, logout, re-login and backup the configuration. Reboot the router. If your configuration is not there, restore from the backup.
• Wait until your DSL connection is up. Verify that the DHCP range is the desired one.
• Change router's IP:
  • Empty all the fields of the IP and select a "Custom netmask" (BTW, it's 2023, netmask is obsolete).
  • Empty all the fields on the DHCP range and retype them. Every single one, even the 0 or the 1s.
  • Reboot.

This will result to the desired configuration in most of the cases (3/4 attempts where OK).

Still any attempt to define a Static IP at any point means that the router will have the default IP and DHCP ranges no matter what you try to do.

FYI, I used both Firefox and Chrome and I tried both Private/Incognito and plain sessions. The issue is on the "server" side.

I have downloaded the latest version of the Firmware, although the router says that its firmware is the latest.

I am frustrated, but you can definitely count on me if you want to debug the issue even with an experimental FW.

Update after the firmware upgrade.

Most settings are saved without breaking the IP configuration.

I haven't touched the LAN settings though so I don't know if something there is broken.

Still I am disapointed from the machine. Connection speed is lower from my previous Ancient Zyxel. WiFi is really good though. Almost impressive.

After a couple of months I return to this post with the hope that someone from TP-Link will pick it up.

I still have major issues with the LAN settings that are reset if I change anything at the "Internet" settings. I use the latest available firmware (0.8.0 0.9.1 v006c.0 Build 220512 Rel.41022n).

I am pretty much sure that this is a UI issue. So, is there any way to configure the router from the CLI?