Did your Server previously have a fixed IP address? If so, is that in the same subnet as the DHCP server in your new router provides to your network? Can you post the IP addresses of your Clients and Server. Check the lights on your Server network card to
ensure that was not damaged at the same time (I know you say it shows up on the router DHCP list).
Phil P.S. If you find my comment helpful or if it answers your question, please mark it as such.