Why is the port open on the router?

Question

network hardware

I bought myself a white ip and set up several services (forwarded ports on the router). Today I discovered that some ports are open on the router that I did not forward. In this regard, a natural question arose: who opened these ports? Why were they forwarded to the correct computer? How to close them? Shouldn't the router block all ports except those manually forwarded?

Answer 1

UPnP