You can find the PPP Settings at Interfaces → Assign → PPP.
PPP can only be configured on top of:
- WWAN Physical Interfaces
- Modem Serial Ports
PPP is commonly used for Cellular modem dial in connections.
Username is the PPP Username
Password is the PPP Password
Assign to new Interface is an option shown when you create a new VLAN and it will automatically assign the Interfaces as described in Assign Interfaces.
If you bought your VT AIR with LTE, you can configure it with the following settings:
HWInterface wwan0 Port /dev/cdc-wdm0 Data Port /dev/cdc-wdm0
Add the dial in data of your provider and assign the PPP to an interface.