@TP-Link Should I buy the m9 plus or x20? Why? Hope you can answer me based on the C5400 router information I provided. I want to fully utilised and yet future proof my investment.

I am using a C5400 connected to an ISP modem. I am experiencing dead zone in some parts of the house so I am planning to get Deco to extend my network. With C5400 running on tri-band (2.4Ghz, 5Ghz...