Avoid using SMS for your 6-digit code if you need portability. SIM swapping attacks are common, and international roaming often fails. Switch to an authenticator app immediately.
This is often a time synchronization issue. On Android: Open Google Authenticator → Menu → Settings → Time correction for codes → Sync now . On iOS: Ensure your phone's date and time are set to "Set Automatically." 6 digit verification code gmail portable