Trying to use Cellular mode but defaults to Tether

Hello, I have the Slate plus router (GL-A1300) and I bought a USB modem The ZTE MF833V U4G LTE in particular. The combination works however the router defaults to using tether mode and labels it an android device. This is a problem because I’m using my router with OpenVPN configs and I’ve come to the conclusion that I cannot remote into my home network because It’s tethering. (The same happens if I activate the OpenVPN client on my phone, enable mobile hotspot and connect it to the host computer and attempt to connect to the client/target. So I am assuming that If the device is tethering, you aren’t able to use the VPN fully. I may be wrong though)

I tested this out by using the hotspot on my phone and connecting it to the repeater mode on the router, then turning on OpenVPN on the router, (not the phone) and I’m able to remote into things. So my thinking is if I can get it to recognize cellular mode, it may work.

How do I get it to recognize the device as a USB modem instead of basic tethering?

It apperars the ZTE MF833V only works in tethering mode, which is not controlled by the GL.iNet router:

Try looking unto AstroRelay.

I do not work for and I am not directly associated with GL.iNet