Either the up/down focus arrow does not respond (only 1-10 digits changing), or the value runs away (even when set on slow), up to 150(200 points. Setting initial focus position by tablet and wi-fi, there is always this time lag with nearly no response or too much (test this at slow 2.4 GHz wi-fi!).
Would be nice to have a quick horizontal slider (kind like the arrow at the the image histogram) to change the value in total between zero and max, when pressing on the digit between then up/down arrow of the focus value.