How to assemble an access point (from internet to local network) based on RPI?

Question

linux

Good day.
There is a need to create the ability to connect via the Internet, via ssh, to machines that are on a local network where there is no Internet access.
There is RPI, yota usb lte modem, linux on board rpi (I can roll something else), local RPI connection to the local network via ethernet.
I tried to connect RPI to lan and wifi networks together. The hostname shows several IP addresses from several networks, but when connecting, priority is given to lan or wifi, depending on the index in the table (iptables seems to be).
Now you need to make friends ethernet connection and yota. I found some tips about sharing RPI on the off page: https://www.raspberrypi.org/documentation/remote-a...
But how exactly to assemble this model as a whole, so that, having got on the RPI, you can connect to any known IP in the local network?

Answer 1

If I understood correctly, then you want to do something like UPnP on a Linux router.
The linux-igd package is suitable for this.