Just purchased a TP-Link Deco P9 (3-pack) today from Amazon (other vendors are available) for £149 and have hooked it up seamlessly with my existing NowTV (fibre 76Mb) without having to do anything untoward in terms of turning off the original wireless router (by making it act like a bridge).
Very straightforward. Download the TP-Link app, plug in the main unit - register it via iphone using SSD of unit - then give your new network a name (SSID) and away it went. Add more units as you desire - super easy to control / extend via the app.
I am doubly happy with this set up, as the (iphone) app allows full control of the devices via profiles (akin to people) with ability to throttle, blacklist, age-constrain and review all of the devices. There is also one-touch disablement if the kids are not playing ball and you need to remind them that t'internet is a paid-for utility and not a god-given right.
One final comment - if you go for this, worth RESETting your network SSID to <something_else> first and then give the Deco P9 network SSID as your original (with same network credentials) so that you do not have to reset/reauthenticate the existing devices.
Might post a follow-up once I have validated my SONOS also works - although my various Alexa's are all happily connected and performing
