I have a 1200AC BT Dual Band Wifi Expander which solves all our dead-spots and drop-outs, its dual band 2.4GHz and 5GHz, solves the problem perfectly.
Currys currently have a deal, price was £59.99, now just £29.99
HERE...
Not as good as the new BT AC2500 unit, but its nowhere near the same cost.
These units are great if you want to boost your home network wifi coverage, for when sat in your car on the driveway using your android double din.