If your device support 4G, then try AirVoice 4G APN Settings for your device. We shared here AirVoice APN Settings, which is easy to setup.

AirVoice 4G APN Settings for Android

To setup AirVoice 4G APN in your Android mobile/Tab, Go to Settings > More > Cellular/MObile Network > Access point Names > + ( to add).
Or, Go to Settings, Connections, Mobile networks, Access Point Names, Tap on Add on the right top corner of your Android. After that Fill up the below information carefully:
Name: Internet/MMS 2
APN: att.mvno
Proxy: 66.209.11.33
Port: 80
Username:
Password:
Server:
MMSC: http://mmsc.cingular.com
Multimedia message proxy: 66.209.11.33
Multimedia message port: 80
MCC:
MNC:
Authentication type:
APN type: default,admin,fota,mms,supl,hipri
APN protocol: IPv4/IPv6
APN roaming protocol: IPv4
Bearer: Unspecified
AirVoice 4G APN Settings
AirVoice 4G APN Settings

Restart Android to apply new 4G AirVoice APN settings.