If, whilst in your house, you are coonected to the internet through Wi-Fi, and loose connection whenever you are outodoors, then your mobile data setting must be disabled. You could try
these tips I posted a long time ago. Their title might confuse you, because they address problems when downloading applications from the Android Market. However, they have a general nature, regarding access to the internet via mobile data plan.
Hope they might apply to your case, somehow.
Anyway, please, let me know if I can assist you any further.
Regards,
Carlos