First of all: Check whether the settings of mobile Internet are still correct. You can double check on this page (This should solve 90% of all the cases). If it still doesn't work, please try these steps:
- Restart your device several times as soon as you arrive abroad.
- Try to establish the connection with the different local networks manually through your device settings. One network may provide a more stable connection than another.
- Check whether the option 'data roaming' is enabled in your device settings. This will usually be available in the 'Mobile networks' menu.
- Don't forget roaming costs can sometimes run pretty high. Check all the rates here.