Is the new router the same brand as the old one? If so, you probably won’t have to change the IP address of the dvr at least. If it’s a different brand router, you’ll have to reassign the dvr a new IP address within the routers subnet, and then re-forward the ports in the router that you have setup in the dvr. Either way, you will have to re-forward the ports in the router for sure. And if you use the router to input your dyndns host info, just input your account information into the new router under the DDNS menu or thereabouts.