Hi  @David-TP and thanks for the quick response.

I have not tried that, yet. In fact that didn't occur to my mind as I am thinking that the domain name registration is done outside, at tplinkdns.com. So, how the factory reset of the hardware is sending such an information to tplinkdns.com that it could release the domain name? And if so, why wouldn't simply switching off the DDNS functionality in the app wouldn't do the same? Anyways, I think that there should be such a unbind function in Deco app as there is in Tether.

At the moment I am using my three Deco M5s as an additional wifi mesh system behind the BE230, in "Router mode". In that setup it keeps updating my domain name and problem is kind of solved. However, I should actually set them up in "Access Point mode" to extend the wireless coverage of the main network. But in that mode it does not support DDNS.

So, for now it works and I can keep my original domain name. At least as long as my Deco M5 is working. But as said, it is a pity that I cannot keep my domain name if renewing my hardware. Registering new domain name is easy but then my existing SSL certicates stops working, so it's not a solution.

Thanks.