Beware: the bridge for Milight bulbs also communicates outbound to a mystery server for Internet control of the bulbs. The actual RF protocol has been documented and implemented as Arduino code, though, which is what I use for my installation.

https://github.com/henryk/openmili

I have one of these and this is why I blocked the wifi bridge from any outgoing network access. The mystery server then just uses the MAC address of the bridge as the "authentication" of where you get to control the lights via the app.

Having a separate wifi network (and separate VLAN for wired) IoT devices sounds like a good idea, and is something that I'll be doing this weekend...

(Also will port-scan the MiLight bridge to see if it's got any other interesting services on it)

Do you have any details of the outgoing network access, as I couldn't find anything?

You can also remove the wifi part, and communicate with the bridge via serial:

https://servernetworktech.com/2014/09/limitlessled-wifi-brid...

Last time I looked into the MiLight devices, it seemed like the protocol didn't support RGB but instead converted it into a more constrained space - is that accurate?

The JavaScript code linked suggests that it indeed uses 19 levels of brightness and 256 levels of (rotated) hue. [1]

[1] https://github.com/mwittig/node-milight-promise/blob/c52d3e4...

This is correct, if you want to use these for mood lighting you probably also want RGB+saturation as the effect will be much nice. For a cheap bulb that can be controlled programatically these are great though.