Modem E3372 Problem with 7.6 version

[Peterjump]

HI,
At first I had a problem with the router that it was connecting and disconnecting and found to do a router system update.
It’s ok now, he gets to know the router.
Now I need to add a PPP client and I can’t choose USB1 interface, only SERIAL0.
Where is the problem?

Router RB760iGS
Firmware 7.6

I attach screenshots

There is still version 7.7Beta6 available - but I don’t know if it fixes the problem?

Peter

[Peterjump]

Everything works without adding a PPP client.
I have the LTE router connected as a backup of the fiber optic link.

In order for the router to function as a backup after the main link is lost, you need to add:
IP → Firewall → NAT → chain: src, OUT interface: LTE, action: masquarade.

And everything works