Questions: OSPF Adjacency Stuck in ExStart/Exchange State

• What OSPF state is the adjacency currently in, and how long has it been there?
• What are the OSPF interface parameters on both sides (hello/dead timers, area, network type)?
• What are the MTU values configured on each router's interface facing the other?
• Is ip ospf mtu-ignore configured on either interface?
• Are there any OSPF authentication mismatches?
• What does the OSPF debug log show during the DBD (Database Description) exchange?
• Were there any recent changes to either router (firmware upgrade, config change)?
• Are OSPF hello packets being sent and received on both sides?
• What is the router-id and priority for each neighbor?
• Can large packets (close to interface MTU) traverse the link successfully?