Generally most devices scan through network frequencies and connect to the first available - which may not necessarily be the strongest signal! Let's ensure that you have the correct settings on the device. Follow this guide for your device.
Open the guide to page 65
Go to Settings > Advanced > Networks
Add wbdata as the APN name
Unselect the "Enable automatic network selection" toggle
Click "Save" (if the page refreshes return to this page)
To manually select a network, click "Select network manually" and choose the network of your choice.