I have hyperoptic but the router is really bad (2.4GHz only). I have a Home Hub 5 which I've used before and works great as a 802.11AC AP.
For some weird reason though, as soon as I stream from the chromecast to my TV via the HomeHub5 (Chromecast is on the hyperoptic router) the wifi drops after about 1-2 mins (as in totally drops, loses authentication).
Any ideas about this? The HH5 is rock solid apart from that. It's only when I use it to stream media from my laptop to chromecast that it breaks. Really frustrating as 802.11n 2.4GHz WiFi is not fast enough to stream 1080p without a lot of buffering in high motion scenes.