3rd party modems

[Lewjcoolj]

I currently have a Fibre 2 broadband service with a Smarthub router. I'm looking to upgrade to the following mesh system as we have a few dead spots in the house: 

https://www.asus.com/uk/networking-iot-servers/whole-home-mesh-wifi-system/zenwifi-wifi-systems/asus...

The router doesn't have a modem. Can anyone advise me on what modem would be appropriate/recommended and whether BT support 3rd party modems?

Many thanks in advance!

[licquorice]

Huawei Hg612 from Ebay.

BT don't 'support' third party devices in as much as they don't offer any help. They allow third party devices though.