There's a known bug in firmware release 1.0.03.15 onward, (CSCvp94049), that has prevented our organization from reliably using our RV340 routers with Verizon USB730L modems for months now. This modem is Verizon's current offering and is listed in Cisco's compatibility matrix.
The modems work reliably in a PC and an older Pantech UML290 modem works reliably in the routers. I have rebooted to a factory default on both firmware versions 1.0.03.15 and 1.0.03.16 with no improvement in the reliability of the router recognizing the modem, USB amber lights flash intermittently with frequent success on one modem, rare success with the other modem.
Does anyone have a workaround for this? Even better... will this firmware ever be fixed?