Thanks for the help anyway. If you have something for me to try I'll do it. I just hope it can be fixed for the next update, if not I'll have to flash another rom.
Mine is a Redmi Note 3 Pro (kenzo). Must be a bug from MIUI 9.
I didn't make a backup so I have no idea what I will do, maybe wait until next beta in case it's fixed.
I updated my Redmi Note 3 Pro and I'm not getting any data, no 2G, no 3G, no LTE. Only voice and sms.
This is the first time that something happens to my phone.