Worked on the openssl/openssl repository to enhance QUIC protocol reliability by addressing a critical issue in ACK handling. Using C programming and protocol design expertise, implemented RFC 9000-compliant logic to reject acknowledgments for unsent packet numbers, thereby preventing loss-detection corruption and improving connection stability. The solution involved updating the ACK manager, refining related tests, and integrating changes across statistics and congestion control components. This targeted bug fix aligned OpenSSL’s QUIC implementation with protocol standards, reducing the risk of false loss declarations in production environments and ensuring robust network programming practices for future packet handling and protocol conformance.