Software for turning a webcam into an IP camera or remote monitoring via the Internet?

Question

CCTV

Good afternoon!
I am looking for software (preferably free and not cloud services) to turn an ordinary webcam into an IP camera (connected to a laptop) and watch from a smartphone.
One of the problems is the webcam behind NAT, there is no access to the router settings.
Why is it necessary - to observe the operation of the 3D printer, which is at work in the back room,
so that in case something went wrong, ask to stop.
PS The option to buy a ready-made camera with a SIM card for access to the Internet was considered, but a little expensive for me.