Solved it! Plumped for a "Western Digital TV Live Streaming Media Player" for £65 from amazon. Plugs into HDMI on TV and has wirelessly picked up my Mini DNLA server which is on a USB hard drive connected to the Router (Netgear 3500 with modfs and AMod custom firmware to enable media server capabilities). Working flawlessly and also has iPlayer too! Happy days.
OnePlus 5T review: Hands-on