@Jetpilot45,
Using both scenarios you listed, the Meraki MX should start using the connection if the USB modem is setup properly. Test the connection with Windows. Ensure the proper APN is set for your Mobile Device Number feature set, if it's a dynamic NAT'd IP then your
APN should be vzwinternet, if you are not sure contact your verizon sales rep or call into customer service.
If you are using the USB730L with a different carrier you will deffently need to login to the modem UI and set the proper APN.
You could try current beta firmware 14.17 to ensure the modem is integrated, 13.25 was before the USB730L was considered supported by Meraki.
When pursuing support of a MiFi device first contact your carrier, if you are still stuck you can contact the MiFi support group.
VZW - Customer Service
or dial *611 from your mobile phone
Mon - Fri, 7 AM - 11 PM local time
Sat - Sun, 8 AM - 9 PM local time
Inseego MiFi Support:
888-997-5211
To force the MX to use USB as the primary, ensure no other Ethernet is connected at WAN1 or WAN2.
Still stuck? contact Meraki Support!
Good luck, and Check back with the community to let us know how it went!
Jeremy