Questions: TCP Connections Reset After Idle Period

• How long do connections survive idle before being reset?
• Is there a stateful firewall or NAT device in the path between client and server?
• What is the firewall's TCP connection timeout (conntrack timeout)?
• Does the application configure TCP keepalive, and if so, at what interval?
• Do tcpdump captures show RST packets, and from which direction?
• Does the same issue occur when bypassing the firewall (same-subnet test)?
• What are the OS-level TCP keepalive settings on both client and server?
• Are there any firewall logs showing connection entries being removed?
• Does the application use connection pooling, and what is the pool idle timeout?