@winac 

Hi,

How does the Archer A5 reject the entered password? Does it directly say "Incorrect password" or does it just reload the Web UI asking for the password again?

  @woozle 

No, it does not explicitly reject and does not show any messages. The login page just submits as a normal login process, but then the same login page displays again.

  @winac 

Perhaps try to setup the Archer A5 using a smartphone or tablet with TP-Link's "Tether" app first. Then, once an Internet connection is established check if the Tether app reports a firmware update being available.

Joseph-TP

All of this were the first things I tried. Nothing did help.

@woozle 
I appreciate the idea. I'll attempt to set up the internet connection and install a firmware upgrade from a smartphone.

  @Joseph-TP 

I confirm I reset the router as you describe. Though I still do not have the router working, now I have the knowledge - why.

After I enter the admin password in the web interface, one of the requests to the web UI returns a 500 web error.

I'm 99% sure that is the source of the troubles.

  @winac 

I find it weird that the router firmware is not able to determine the "Model No." of the router.

Near the top of the webpage it should read  Model No. Archer A5  .

Would it be possible for you to return the router and get it replaced under warranty?

  @woozle 

I made an effort.

However, the router is deemed a "Complex electronic device" under the rules of my country (Russia), and before the vendor can accept it back, it must be inspected by an approved technical center.

Although it seems like I might do it, I do not think the cost of the router worth spending half a day transporting it to a technical center and again half a day retrieving it.