Does the Server have IP Addresses statically assigned to each NIC's port or what?
Does the Server receive IP Addressing dynamically via a DHCP Server or what?
NIC Software Driver (and Firmware) version are OK on your Microsoft Server 2012 R2 installation?
First learn how to troubleshoot one port connectivity at time, then - eventually (if necessary for resiliency/throughput) - you can deploy NIC's ports (switch independent/dependent) teaming.