Firstly, make sure your modem still work properly. Then, try to restart your router and modem. If still no success, better to contact tp-link support to help you reconfigure the router.

TL-WR940N(ES) version should be the localization version which can't update other version. That's why you meet that error code. I consulted this similar issue with tp-link support ago even though...

Hey afi, we can't update the firmware with different hardware versions. Therefore, there is no any relationship even v4 firmware fix the problem if the hardware version is not the same one.

better to email tp-link support directly with your configuration screenshots.

luizenger wrote I also bought TL-WR941HP to use it as a range extender and had the same situation. After putting my main router to work at a free channel, and also changing the IP of the TL-WR941HP...

miki0071 wrote But where do I find the latest firmware version? in this page only the configuration guides are available. To change the channel of the main router, should I use one that is not...