Camera Event Footage Over Internet to Remote NVR

[Barboots]

Moving discussion regarding this from another of my threads.

I am putting 3 Dahua cams up at a house I need to monitor. I plan on using cameras with SD card recording, plugged in to a old OpenWRT router and sending event footage out via a Nighthawk 4G LTE mobile router. I want to bring that in to my home Dahua NVR, which is behind an OpenVPN equipped Asus router.

I'd appreciate any methods to achieve event recording between the devices.

Remote Site:

• Dahua 5442 T-ZE (not yet purchased)
• WNDR3800 running OpenVPN under Gargoyle firmware Gargoyle (router firmware) - Wikipedia
• Neatgear Nighthawk M2
• Telstra 4G LTE mobile network

Home Site:

• Asus RT-AC88U running OpenVPN
• POE switch
• Dahua NVR4116HS-4KS2

The Nighthawk router is one of the small, portable units and can not do ZeroTier... and to be honest, neither could I. Any suggestion on making this work?

Cheers, Steve