Choosing & Configuring VPN-Compatible Router for Orange LTE Network with B315s-22 & No-IP

Hello.

I have a LTE mobile internet package in the Orange network and a b315s-22 router from the plus edition. I have a public dynamic ip address and I use no-ip redirect to get static ip. The configured APN-VPN router is connected to the network download speed + \ - 30Mbs upload similarly

The question is what equipment (router) to buy and how to configure it to use it
with vpn I have monitoring (here the possibility of operating on ports I have already done it on B315) and control of the apartment via a web server, so I must be able to connect from the outside, I do not want to put anything on an additional computer in the apartment, hence the idea to use the implemented hardware options in the router.

I do not want to make no sense in the cost of the solution would be 4GAC-68U, but in a year the mobile will be abandoned in favor of the cable. So the option below is better but ...

I had RT-AC68U for a while, but I couldn't configure it to avoid double NAT, I also found posts about problems with working with 4G modems. I asked for ASUS support, but without any particulars (there is no point in writing).

Another idea is something from the FRITZ! BOX family with built-in VPN support.
It is not the choice that is the most important and how to make it all work, I will not describe my activities so far, I am asking for ideas and together we will try to implement them, I do not want to buy another equipment that will not work as intended. Possible screenshots of b315 settings if needed or https://www.youtube.com/watch?v=2WgMzN-WLs8

Modern CCTV or smart home systems only need access to the Internet and the rest works through the cloud or p2p. It is easier and safer. What exactly do you have for your hardware?

As I wrote, I am not interested in another solution. Yes, monitoring can be done, as I know about the subject and I've already done it. But I am not satisfied with this solution. The project is wide, control self-written server, concentration control of heating, lighting, alarm and monitoring, and I do not know what will be added over time.

So it remains to buy a router with the possibility of setting up a VPN server, I would look towards Mikrotik for a more complex system.

Ok, I also considered this purchase. However, I would like to ask for tips on what model is worth buying (personally I would prefer FritzBOX) how to configure it with b315 because it provides access to the LTE network. With ASUS, with the USB modem plugged in, I couldn't get rid of the double nat, when I changed the configuration, I lost the connection to the network. I wanted to use a different modem, but ASUS support could not match the list of currently supported LTE modems in Poland. I found on the electrode forum that DMZ settings can be the solution ??? I would like to ask for some specific direction on the topic I am currently dealing with, but within 2 months the topic will come back.

If a VPN server is in friction, get it.