I am creating IoT gateway following instructions from JN-AN-1110-Jennet-IP-Border-Router. I use Beaglebone Black as the hardware platform. The hardware runs on Debian 7.9 with kernel 4.1. The IoT gateway can work but it is not stable. In normal running, we can send and receive data from the TUN device through the Internet stack. However, we encounter a problem whereby in some situations, we can send data through the Internet Stack to the TUN device but we cannot receive data from the internet stack. Sometimes, restarting the network interface solves this problem but sometimes it doesn’t and we need to reboot the OS which also sometimes doesn’t solve this problem. 2 attached pictures show the network configuration and radvd configuration. Could anyone help me to solve it?