I had a look, and all I actually needed was a range extender, which turn out to be half the price. I got a RE220, seems OK. The one difference is the AV600 had a pair button which takes 3 seconds to...

@ErkanB Mine has just started doing the same thing. I bought it from Takealot in South Africa in August 2018, so it did work perfectly for just over 3 years. I have no idea what warranty tp-link...