

Yeah, I even wrote TP-Link an E-mail about this, but they wrote back that that was just how the device worked, that they could not recommend any of their mesh solutions which could provide a stable WiFi connection even without internet, and that they obviously couldn’t recommend any devices from competitors.
My image of TP-Link might have taken a hit as result as I believed this to be a fundamental and implied feature.
I returned them. And I did indeed get the name wrong as they are a series of WiFi mesh towers named ‘Deco X20’ and not ‘Deca’.
I do already use DD-WRT in my home network, but these were meant to provide a network-on-a-budget out in the field, aka. a stand-in for professional solutions which other people should be able to set up too, so I wanted to modify them as little as possible.
WiFi extenders do technically fit my requirements (and I’ve got them working mostly successful), but, as far as I’m aware, mesh is specifically made for the purpose of having a seamless WiFi device transfer from one tower to another, and where one can form a circle or “spiderweb” pattern with the signal taking the best (distance/speed/reliability) route back to the router - which is what I need.
Ubiquity seems to have gained traction lately, so I’ll throw them an E-Mail whether their devices are too smart to be usable too.