Direct IP support for Netgear AirCard 320U and other LTE modems
Direct IP is the new method used by many LTE modems as PPP, with its overheads, can only support 25mbps downstream, whereas Direct IP does not.
I have tried using my Netgear AirCard 320U with my home-licensed UTM without success, and it took a great deal of troubleshooting to find out why.
It seems that /dev/ttyUSB2 (which UTM picks as the port to use) is no longer used for PPP control. That has been relegated to /dev/ttyUSB3 for backward compatibility. Instead, the configuration is done using Direct IP, which uses DHCP instead of IPCP for IP addressing.
My attempts to use PPP/IPCP were near fruitless - I did so by renaming ttyUSB2 to ttyUSB3 and vice versa, which worked for about 3-5 minutes until udev restored the files to their original names.
In my investigation for another solution, I stumbled upon Direct IP.
To connect using Direct IP for supported devices (such devices will create an Ethernet-style network adapter called wwan0) is as simple as the following:
1. Turn on full functionality:
2. Set up the APN to use.
3. Enable the profile
4. Run dhclient on the wwan0 interface to get the IP address.
1. Run dhclient -r wwan0 to release the IP address.
2. Disable the profile.
3. (Optional) Turn off the radio.
It really is that simple.
One final note: do not, I repeat DO NOT, use kernel 3.10.x for this, as Direct IP support appears to be broken.
Thank you for your consideration.
Aaron Mason commented
I just tested Direct IP on kernel 3.10.25 and it appears Direct IP has been fixed.