Thank you so much @BearWithBeard for this, it's really helpful. I decided to try using a serial gateway and have had more success. The sensor is connecting and getting an ID from the controller. Although the gateway drops out when i reboot my Pi and I have to unplug, reconnect and restart HA! Not the end of the world, and certainly better than no connection, but a bit annoying. I'd like to use an Ethernet gateway if I can so I'll try your suggestion of static ID's and see what happens. I like the idea of organising things as you suggest, so may well end up doing that anyway. I'll try the static route to the gateway too if still no luck - very useful info. I'm using Uno's at the minute while I test/set it up and am powering them via USB from a laptop (sensor) and an NUC (Gateway). Although my serial gateway is connected via USB to the Pi running HA. No capacitors at this point either. They are within a few metres of each other so don't think range is the problem. Will amend my HA Config as you suggest, again useful info. Only other thing I didn't mention is I'm using a 5100 shield breakout board on the gateway rather than the board in the tutorial, not sure if this affects power or is relevant! Again, thank you, really appreciate your advice! I was completely stuck so really nice to have options now.