After the recent update, my DNA starts to have mobile data connection problem. Often it shows mobile data disconnected. Turn off then turn on does not solve problem. After restarting, it shows 4G LTE, but I can't connect to any website. Then after several minutes, the symbol changes to 3G, and I can now connect to internet as normal but at 3G speed. I have taken out the sim card and put it back, still same problem. What may be the cause, what should I do? Thanks.