The problem actually started 6 months ago. I'm not sure if it was due to a power outage or a firmware update. I've tried everything, swapping the nodes, resetting the network, deleting the app,...

Last year, I bought 2 TP-Link x60 Wi-Fi extenders. I placed one on the ground floor and the other on the upper floor, connected by an Ethernet cable. After around 4 months, the extender on the upper...