CompTIA Server+ SK0-005 Practice Question

During scheduled maintenance, a systems administrator notices that production servers can ping their default gateway and other internal subnets, but cannot reach any external IP addresses or hostnames. A tracert 8.8.8.8 shows the first three hops-the core switch, the perimeter firewall's inside interface, and the firewall's outside interface-responding within normal latency. The trace then stops responding at the first upstream router owned by the company's Internet service provider (ISP), and every subsequent probe times out. A branch office that uses a different carrier reports no issues reaching the Internet. No access-control lists, VLANs, or routing tables were changed during the maintenance. Which action should the administrator take NEXT to restore connectivity?