I modified my new Xiaomi v3 Gateway (round marks) with round marks to respond to OpenHAB as mentioned here [SOLVED] Openhab2 - Xiaomi Mi Gateway - does not respond. I can now include it, and it will report the current devices and measurements. But somehow it gets disconnected after 5min, with no updates to sensors until then. Once I change something in the bridge config (eg the ip) and change it back, it will connect again and report the correct values, but only once until disconnecting again after a few minutes.
This is only for the 2nd gateway (I have two). The first v3 gateway (square marks) works fine. Running on 2.5.0M1.