intermittent wifi issues MacBook Air

Bought Mac Air 13"end of 2016 and had no issues connecting anywhere to wifi and staying connected.

Over the last couple of months, I've noticed an intermittent issue while surfing the internet both at home and at other locations.

Wifi signal is always at full signal, only option is to restart macbook.

So far Apple and I have:

- reset the SMC (system Management Controller)

- replaced WIFI controller

- reinstalled MAC O/S

- replace home router (ISP confirmed latest software, disabled Smart Wifi, enabled separate 2.4 & 5Ghz frequencies)

- enabled wifi logging

- submitted data capture both from home and in store

- assigned static IP (no change)

When issue appears, I open terminal session and unable to PING default gateway. Times are random and there is no specific website which triggers this.

I have Applecare and customer relations is basically telling me there is nothing more they can do - it is an environmental issue regardless where the issue affects my macbook air. What I believe I have now is a "lemon-air"

[Edited by Host]