Hi Paady , Nice to meet you.
Looking briefly at your post I was wondering how many devices you have connected to the TP LInk W9980 ?

The W9980 is a combined modem/router . It is very capable of handling BT Infinity packages. However, like most modem / routers they are only able to handle successfully 10 devices. something to be awre off when all the family try to connect at tea-time.

Without looking at your house and the size and thinkness of your wall I am unable to comment on why you get drops of internet.
My best guess would be because of signal interference with the wifi.
Wifi signals are a bit like the old transistor radios I had as a kid. I wanted to listen to John Peel but could only do so if I stood my transistor radio on a stool to get the best signal.. then it would disapear so I had to stand on the window sill .

All sorts of things can interfere with your wifi Signal. Your Neighbours TV , Christams tree Lights, The central heating .. the local cop car out side. This is called EMI or Electomagnetic Interference .

What I can say is the Tp Link w9980 has a very good wifi range and if you are finding wifi blackspots then it is probably just the signal trying to catch up or the dynamic assinging of IPs in delay.

Anyway good luck
Hope this helps some

Kind regards
Millie