Raspberry Pi 3: SIM7500 Module Internet Connection

Follow the instruction of this page, after the last step, need to add ppp0 to the default route.

[Updated] Tutorial 3 | Make a PPP internet connection with 3G, 4G/LTE Shields on Raspberry Pi

route_found=$(/sbin/route -n | /bin/grep -c ^
ppp_on=$(/sbin/ifconfig | /bin/grep -c ppp0)
if [ $route_found -eq 0 ] && [ $ppp_on -eq 1 ]
  then /sbin/route add default ppp0