WE826-T Fixed Wireless Double NAT

I hope this is in the right place for this post.

For a couple of years, I've used a fixed wireless ISP, switching from satellite. I switched mainly to be able to play games online. It's worked great for my laptop, never had any issues. I recently bought a PS4 because I have a couple friends who don't have PCs. I've never used OpenWRT until now, and do not know much about networking at all.

My router is a ZBT, model WE826-T. From what I've read, it seems that the modem is installed inside the router. I think I'm getting double NATed because of this.

I've scoured the internet over the last two weeks trying to find answers. Some of what I read is for the USB dongles or phone tethering. That is not what I have. I have a 4g antennae on my roof connected to the router via cables. The router has the SIM card in it.

I've forwarded all ports to the PS4, set a static IP with the Playstation's Mac Address, but I'm still receiving a closed NAT. Due to the current pandemic, my ISP's tech support is not available, and neither is Sony's tech support.

I've tried setting the router up to have a DMZ zone, but after following the instructions, my wifi signal stopped working and the wired connections stopped working too. I've also thought about setting it to Bridge Mode, but everything about OpenWRT is pretty over my head. I broke out an old router, but can't find the 12v power supply, so that idea is pretty moot at this point, anyway.

I'm now wondering if I could purchase an LTE modem, put my ISP's SIM into it and use the 12v supply that the OpenWRT router is using to power my old router, and connect that via ethernet to the modem. I understand that if it's just a modem with no router, everything would pass-through it and into my other router. The modem would have to have the antenna ports (I don't know if these are standard, or if there are different sizes/threads) because I don't have good cell service in my house.

Am I correct in my thinking? Or, is this just technical and over my head?

Thanks in advance.

Usually mobile operators are using CGNAT.
This means that they are already doing NAT. You can verify that by looking at the wan IP address. If it is starting from 10. , 172.16-31, 192.168, or 100.64-127 then you are unlucky.

So, if my IP is, then there's nothing at all I can do?

This is the lan IP on a default OpenWrt installation.
But yes, if the IP belongs to the private range of IPs the best you can do is call your ISP (not Sony) and ask if they could forward a few ports for you.
Don't keep your hopes high though, they are thousands of mobile internet users and they wouldn't want to take this extra workload, set aside the limitations.

Look at the WAN IP that OpenWrt gets from the modem section.

The modem is a separate unit inside the WE-826 box. It has its own CPU and its own configuration. Usually it is also acting as a router, though you may be able to change that.