It's been related to me in the past that the 3G/UMTS network stack is famously insanely complex and that the 4G/LTE stack is noticeably less so. So that might

It's been related to me in the past that the 3G/UMTS network stack is famously insanely complex and that the 4G/LTE stack is noticeably less so. So that might factor into your trouble with 3G and Bellard's success with LTE. :)