Bash script posted by the developers on github to bring the modem back:
#!/bin/sh
set -x
sudo rmmod xhci_plat_hcd xhci_hcd
echo 0 | sudo tee /sys/class/leds/wwan_en/brightness
sleep 2
sudo modprobe xhci_plat_hcd
sleep 5
echo 1 | sudo tee /sys/class/leds/wwan_en/brightness
This works for me but there is a another modem or kernel patch that is needed ill look for the link. It will still every say 30minutes loose the modem but typically come back. The script i have to run say every 2 days or so.