Wifi to Mobile Data Switching Issues on 5.1.1

Since updating to 5.1.1 (Stock, clean install, UB) I have connection issues. Usually happens when switching wifi off or leaving a wifi conected zone, mobile data does not switch on most of the time or it takes a long time to turn itself on. As far as I have read it seems to be a 5.1.1 bug ( see https://productforums.google.com/for...us/o-UyGECxh2k )

Does anyone happen to know a fix?? Has anyone had a similñar issue on Xperia Z?