@kejianshi:
The ideal solution would be to use something like a hardware wireless client that also has several ethernet adapters that you can plug your cameras into.
Why are you wireless only? Are you double NATed?
(sorry - pic didn't load at first)
Looks like your VPN server is in the wrong place to make this happen unless its a bridged network?
The VPN server is at my local site. So, I guess technically a site-to-site setup would work, but would require another pfSense box on hand and in the same cabinet. Then I would need a small private LAN for the Windows PC and the Camera Recorder.
I am single NAT'ed by the 4G <-> Wifi unit, which is my only access to the outside world (internet). To solve the "no wifi on the video box" problem, I can share the wifi internet on my Windows PC, which then becomes double NAT'd. I don't think that is a problem if I could VPN client out of that NAT system into my local pfsense server, as it would tunnel through both NATs I assume.
I am trying to achieve this without additional hardware, the best I have come up with is a Raspberry pi in a bridge mode, but with a VPN Client connection included that "dials home" to the home office.
This, plus VPN connection:
https://rbnrpi.wordpress.com/project-list/wifi-to-ethernet-adapter-for-an-ethernet-ready-tv/