Cannot switch to 3g network automatically

[erahimi]

My Xperia z2 cannot switch to 3g network automatically. I can switch manually very well. Is it normal? Other brand switch very well in my area.

[Uliwooly]

Do you have the correct APN settings? how old is your SIM card? is it a micro SIM card or did you trimmed it ? Do you have stamina mode on?

[erahimi]

thank you for reply. APN setting is correct.six month old. Trimmed.

[Uliwooly]

That could be the issue, that the SIM card it's trimmed or it's simply acting up, try to get a brand new MICRO SIM card. 

[Phy]

Check if 3G works fine while on safe mode

How to boot on safe mode.
http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008#U348008

[erahimi]

My sim card work on Nokia lumina 930. When I choose wcdma only it works fine but when choose media(proffered)/gsm cannot switch. My friend has this problem too with Xperia m2. This must be Xperia's issue.

[Uliwooly]

Try as suggested above on safe mode, also trimming a SIM card could cause this, it doesn't hurt to get a brand new MICRO SIM card