AmCrest AMDV 10808 : TP-Link AX21 Router

[straightshooter]

I have a house that is located on top of a mountain where there is cable service and has a smaller cellular bandwidth as my ISP.
So far, ever since I installed the AX21, the phone app can no longer communicate with the AmCrest Security Cam DVR (AMDV 10808) when I am not at the house, no matter how I reconfigure it.

Here's the setup:
WAN <--> NetGearNighthawkHotspot cellular device via AT&T
The above NetGear device is set to an IP passthrough so it does not have WiFi, just a dumb device to get onto the cell network and Internet.

Behind that NetGear device is the AX21. So,
WAN <--> NetGearNighthawkHotspot <--> AX21 <--> AmCrest Security Cam DVR

I have even reserved a static IP for the AmCrest Security Cam DVR inside the AX21 firmware config.

The AmCrest DVR uses Upnp and P2P for the phone app to get in. Previously, when the Netgear device was set up to serve WiFi and act as a router without the AX21 router, the DVR app worked fine. But, once the AX21 Router is in place, it cannot get through anymore.

Of course, when I am on premise using the local WiFi provided by the AX21, it worked fine. When I turned OFF the WiFi to go through from the outside, it cannot connect. Very rarely, I can get in on the App but that is more like 1% of the time.

Any idea on how I can resolve this?

[Revo2Maxx]

To be honest it is hard to say.. I know that there are many different ways that a multi router can work. Some with no access to the Internet from within that router and others with access enabled. It almost sounds like the connected router isn't connected correctly for the type of connection are you trying to setup..

Typical type connection is Bridge, Access point and Router. There are different ways that one can make these connections and some will have access to the internet and some won't. if you connect your Cell Phone to the second router is your Cell Phone able to access the internet?

Also with P2P access there should normally be no reason to mess with the other settings like Upnp..

In the end it might be as easy as the second router *Netgear* needing to have the NAT turned off if you have not already done so.. Again hard to say as I don't know how you have your system setup.. I have 5 routers on my network. 1 of them i have setup by design without internet access..