Reduced range on Doorbell 2

Hi,My Doorbell 2 has worked flawlessly for almost a year but the last month we have noticed that the range is severely reduced all of a sudden. To trigger motion detection we have to stand closer than 10 feet even though it´s configured to work between 15-30 feet. I´ve tried different settings using motion wizard but no luck, all act the same way. Earlier it would pick up all movement from around 25 feet. My battery is fully charged.Any suggestions?Regards,John