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.
There are three drop downs: Country, Provider and Plan. Depending on the selection it will prefill several of the following fields with data.
Username is the PPP Username.
Password is the PPP Password.
APN is the Access Point Name.
SIM PIN can be configured if necessary.
Dual SIM Card Support if you have a VT AIR that has two physical SIM card slots, you can utilize the Daul SIM Option. Only one SIM Card can be active at the same time but you can configure an automatic failover in case the Gateway of the connection is down. In order for this to work, please configure a monitoring IP and disable the Gateway option Always Up Gateway.
Options all options above are available again for the second SIM card.
Auto Failover enables the failover to the non active SIM card in case the Gateway of the connection goes down.
Roaming to allow the modem to use roaming.
If you bought your VT AIR with LTE or 5G, you can configure it with the following settings:
Data Port /dev/cdc-wdm0
Add the dial in data of your provider and assign the PPP to an interface.
You can now configure your newly created interface for internet or as a backup connection.
We have a Video Tutorial regarding the LTE/5G configuration: