There is a reset hole underneath the deco, you can simply press it once to reset it. But I don't think that would make a difference. Did you have power outage? If the unit just died for no reason,...

How can you tell your kindles are rejected by the deco in the bedroom? They lose connection when you move them to the bedroom? Have you ever changed the operation mode from router to access point?...

I don't get your point...but it sounds like you need to contact the local support team. https://www.tp-link.com/br/support-contact.html#Hotline-Support

Contact tplink support to see if they have a driver to fix the problem. To verify it's hardware or not, you can change PCI E slot, or install it on another computer.

There is driver for Mac 10.13 now, for model T2U/T2UH https://www.tp-link.com/en/download/Archer-T2U_V1.html#Driver

If the extender connects to the network on channel 13, it won't work? Do you get the RE led? Does the main network disappear or you just cannot find the extended network?