@Andrea68 

You can find a detailed explanation here https://www.tp-link.com/us/support/faq/2598/.

I don't know why you only started seeing this message since 2022, though. Maybe you had not enabled Local management via HTTPS previously?

By the way, the same also happens on routers from other manufacturers that I own, so this is not just a TP-Link issue.

Your other problem with the link http://tplinkwifi.net/ not working should be unrelated to the security certificate. Try if it makes any difference if you type https://tplinkwifi.net/ instead.

Hi  @woozle I turned on HTTPS at beginning 2021 may be something have been changed in browser security checks.

Related to http://tplinkwifi.net/ you are right I need to use https://tplinkwifi.net/. When I turn to https://tplinkwifi.net/ I got a different error message

Chrome

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

NET::ERR_CERT_COMMON_NAME_INVALID
Subject: *.tp-link.com

Issuer: GeoTrust CN RSA CA G1

Expires on: 20 mar 2022

Current date: 25 mar 2022

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Firefox:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Websites guarantee their identity through certificates.

Firefox does not trust this site as it uses a certificate which is not valid for tplinkwifi.net.
The certificate is valid only for the following names: * .tp-link.com, tp-link.com

Error code: SSL_ERROR_BAD_CERT_DOMAIN

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I accept your solution the link you provide is very useful.

Should be a better user experience if TP LINK provide a SW update with only certificate update but I understand that the AX6000 V1 is a discontinued product so, I guess,  no any new update will be distributed in the future.

Many Thanks for your support

Andrea