Henry 
Hi, Have you ever tried 6LowPAN on NanoPi2 ? 6LowPAN is well supported in kernel linux-4.0, however linux kernel version of NanoPi2 is quite old, and there is no mainline release at the moment. I have referenced to linux-3.8 of BBB and patched the kernel source code. By using two modules MRF24J40MA, connect to 2 board NanoPi2s and they could send data packets to each other properly. I've tested with PAN network, but 6LowPAN still doesn't work. If you are interested in it, I'd like to share my patch and we can discuss more about the issue, need help from expert regarding to Linux network stack. Thank you.