@Marios2020 

Actually it works LOL!

For the V5 hardware version and the firmware that comes with it I can connect wireless devices but I can't use the internet.

My smartphones are connected to the router but when I open Chrome and try to go to a page I can't.

There is no internet and I even tried to go to 192.168.1.1 or http://tplinkmodem.net or the sim provider site but I couldn't.

So even if you connect you can't use a browser and the internet and you can't go to the log in page for the router settings.

I don't understand why they allow the connection in the first place but that's the way the Black/Whitelist works!

Here is the answer they gave me :

"Hello Marios,

Try updating to the latest firmware here: https://www.tp-link.com/en/support/download/tl-mr6400/#Firmware

If the issue still exists answer the following:
Are you trying to configure the Whitelist from the Access control feature?

Do you also have access to the internet from your phone?

Please provide detailed screenshots from the Access list configuration

kind regards."

I checked the firmware for V5 that they have in the site and is the same that the router came out of the box

so for V5 nothing changed in the firmware they uploaded in their site.

For now I will use the whitelist as it is but I will contact them again to ask if they will bring back the Allow/Block Menu

that it completely forbids the connection.

I hope this may help you.