How to set up dynamic DNS?

Question

Network administration

I'm trying to connect No-ip for dynamic dns inside the router, and I seem to have succeeded. But for some reason, this ip address (which arrives in no-ip) cannot be contacted in the end (the ip address is the same as what can be seen in 2ip.ru). Is it possible that the router gives one ip address, but another ip is needed to request the router? In which direction to dig?