@d0ugmac1 There is a bit of overlap but if i walk to the far end of the garage, then AP 1 is lost, so my theory says - the AP2, which now has the strongest signal, is teh Ap my phone should connect to , but it just does not connect. Then I manually choose it and connects instantly. Really got me baffled. 

  @d0ugmac1 Hi, if I walk from main router room, to the lounge, the signal drops for a second or two, when signal of main router drops, the phone picks up the signal from the 1st AP and connects - almost seamless. If I then walk to the garage, my signal  from 1st AP drops completely, but does NOT connect to 2nd AP. Then I have to go to my settings, wireless options, and the phone shows all available networks. I then have to manually select the garage AP( 2nd AP) and then it connects. It should be noted that the main router and the 2 AP's have the same SSID and password, which should - by my thoughts - connect automatically to the 2nd AP like it does when i walk from main router to lounge

  @d0ugmac1 Thanks for your advice,  I thought of that, but what changed  my mind, was the fact that the AP that works is the closest to the Asus router and i would have thought that the 1st Ap would give me issues but its the  2nd AP  - furthest away - which has zero signal overlap with the main router. I know this as during load shedding we still pick up a hint of WiFi from the Asus in the lounge - but very weak  signal, so I know there is overlap, which is why i thought that would cause issues with 1st AP. Unless this overlap, and bing on teh same channel - may be assisting in the "seamless" changeover between Asus and TPlink AP. I will try changing the SSID on the Asus and see what happens.