Symptoms: OSPF Adjacency Stuck in ExStart/Exchange State

• Two routers connected via a point-to-point Ethernet link are unable to form a full OSPF adjacency.
• The adjacency has been in ExStart or Exchange state for over 30 minutes.
• Both routers can ping each other successfully.
• OSPF was working previously; the issue started after a firmware upgrade on one router.
• Routes learned via OSPF from the affected neighbor are no longer in the routing table.
• Other OSPF adjacencies on both routers are fully established and healthy.
• The link between the two routers shows no errors or packet loss at Layer 2.
• Application teams report connectivity failures for traffic that traverses this OSPF segment.