no connection to server after servers routers ip has changed

Hello,

got to change the internal network's on serverside router's Ip from 192.198.2.1 to 192.168.2.2(cause need the original IP f. sth else)  and whyever that affects the connectivity from outside(via dydns).

After this router's IP changement cannot connect anymore to the server via VNC. But still can connect to the routers gui via dynds. So there is no fault/problem wit dyndns.

So any idea what may be the cause and how to resolve that is very very welcome.

Thanks in advance !