Avast Real Site blocking me from accessing tplinkwifi.net

Recently, we have received a customer's feedback regarding the Antivirus software Avast.

Here is the detail of the email he sent to us, we hereby share it with our customers: 

As we all know, tplinkwifi.net, tplinkrepeater.net, tplinkplc.net, tplinkap.net are sites of TP-Link management page. Through those domains, we can easily access the management page of our TP-Link products.     

However, after installing Avast Antivirus software, I cannot access tplinkwifi.net anymore, my browser takes me to the “Trying to configure your Router?” page instead of the management page of my router.

My cellphones connected to Wi-Fi have no trouble accessing that page. So I supposed that this issue could be caused by the newly installed Antivirus software Avast.

I spent a few hours wondering what caused this issue and I have eventually found it out. It is the “Avast Real Site” that has been blocking me from access the real tplinkwifi.net, here is an official statement of “How does Avast Real Site work”:

Every time you enter the URL (address) of a website, such as www.example.com, into the address bar of your browser, the URL is translated to the IP address (Internet Protocol address) of the web server where the web page that you want to access is stored. Real Site provides an encrypted connection between your web browser and Avast's own DNS server to prevent hijacking. In other words, Real Site ensures that the displayed website is the authentic one.

So I took a little experimentation on it, here’s my results: it seems that my TP-Link Router intercept one DNS query (tplinkwifi.net) sent from my computer, respond it with its own IP address, then my computer gets the IP address of the TP-Link device and could successfully access the management page. It doesn’t intercept other DNS queries, only the “tplinkwifi.net”, I have another TP-Link Range Extender in my house, this extender doesn’t intercept “tplinkwifi.net”, but “tplinkrepeater.net”.

In other words, Avast has taken control of this computer’s DNS queries, all redirected to its own DNS Server, and the DNS Server of Avast resolves the “tplinkwifi.net” to an official public IP address of TP-Link, not my router’s LAN IP address, this is the root reason why I got the page “Trying to configure the Router”.

After disabling “Avast Real Site”, the DNS queries became normal, I can manage my router and extender from tplinkwifi.net and tplinkrepeater.net again.

For those who has lots of TP-Link extenders or powerline devices, I would not recommend using such function as “Avast Real Site”, because those devices are not like routers, routers have its own fixed IP address, those devices’ IP addresses are not fixed unless we make it so. With “Avast Real Site” enabled, I can still access my router’s management page through the IP address, but I have no idea what is the IP address of my extender.