Router plus mesh (node)

Hi – I hgave an Asus RT-86U and bought one of their Lyra nodes. It has automatic set-up within the RT’s UI. The node gives itself an IP address and channel (neither can be manually set). However as soon as it’s set up (wirelessly) wi-fi disconnects after about 2 minutes. As soon as I unplug the node, everything is stable again. I cannot work out why it’s doing this. Any ideas please?