We have isolated the problem.  the bands are ok.   the problems s that the phone is unable to switch betweeen 4g and 3g.  i had to manually constantly switch that over. 
I found another thread with same problem.  hope you guys sort this out on the near future. 

same happening in Colombia after last update 

bands are ok,  the problem is when the phone needs to switch from 4g to 3g and vice-versa.    this is just happening after the wireless update. hope you guys release the flash settings so i can get the wonderful phone i had before. 

I spent some time with technicians from the operator. the problem seem to be on one of the bands ..  How can I be sure all the bands are open for Colombia? 

Ii did complete another factory reset, the problem persists on 4G LTE Movistar,   on other sim cards and networks it works fine.  is there any option to roll back? or have a new update with this sorted out?  I am really struggling and desperate to have the working well for my work. 

hi there,   same happens to me on just one of the sim cards,  i have issues connecting to 4g on Movistar Colombia.   is there anyway to roll back to previous version which was working very well?  i am not having the same problem with sim number 2.   i already did a factory reset and didnt  work. :ro...