@David-TP 

Hi, thanks for the reply

I have to mention that I did the test with the beta version file that you sent me by private message, unfortunately I still have the same Error (Failed to upgrade the firmware. Please check the configuration file and try again.

) as in my previous posts.

I did the procedure with the factory restored repeater, connected by cable to my laptop, using the browser Chrome and selecting the beta firmware .bin file. I don't understand what could be happening, would there be a way to check the integrity of the firmware when I unzip it? 

  @terziyski 

I have tried each of the suggested ways with each of the firmwares ( downloaded from the official links, the links shared here in the thread, and with the beta firmware shared by @David-TP : Wireless from the mobile (two different mobile phones both with Android and a Huawei tablet with ArmonyOS) with the mobile browser and/or desktop toggle active, even renaming the file to the way you suggested in a previous post.

Wirelessly with the laptop (windows) and the browser (chrome and edge)

Wired with the laptop (with different cables from the different tp link devices purchased) the same as above.

Is there a way to upgrade via console? maybe i could try force by command

  @David-TP 

I have had the repeater for almost 9 months, purchased through Amazon.

The reason why I want to upgrade it is to be able to use the easymesh function added in new firmware versions with an easymesh network that I already have working (and expand it to another place): two archer ax53 routers (one ax53 as main router and the other as satellite) and an RE315 repeater which are working together without problems with each other.