Can the ER605 Web Filter according to the WAN Port?  I went into Web Filtering and all I see is IP Group for the LAN.  I don't want to block the data all the time just want to block it when on Cellular failover/backup.  I'm just not sure if I'm missing or overlooked something.

Essentially I want to block what I consider unnecessary traffic from going out on the USB Modem (WAN2) only.  We have a cellular backup option plugged into the USB Port, however it's limited to 20 Gigs.  I want to use the webfilter to block all the Social Media crap and Video Streaming sites so the wife and kids don't use up all the data on WAN2 should the primary internet go down. 

Thanks in advance,

J