On Rut240 last firmware, RUT2XX_R_00.01.11.3.
If ppp interface goes down, you have to restart firewall by hand to recover the connectivity.
You can test it easily; connect a pc to rut240 lan port, launch a continous ping to an external ip address (google or something like that), remove the sim card, re-insert the card, and then, the ping is never recovered, but you are able to ping any other address. From rut240 (via cli) it doesn't happen.
That behaviour isn't present on previous firmware versions.
