Due to IPv4 address exhaustion, IPv6 deployment has been in progress and the transition from IPv4 to IPv6 has become more imminent. In this article, we report an on-campus IPv6 beta site coexisting with IPv4 networks and designed with requirements from its stakeholders. We conducted a wide range of test cases, from essential functionality tests to advanced stability tests which require complex interoperability tests and cannot be performed in laboratory testing. After one year of operation, tens of defects were observed and seven representative defects in dual-stack tunneling, IPv6 routing table, RIPng, and OSPFv3, are reported. Most defects are reproducible, and some could be fixed by proper configuration while others are caused by flaws in system design, memory management, or protocol implementation. We suggest careful configuration, overloading prevention, limited resource sharing, and robust error handling as the lessons to vendors and administrators of IPv6 devices.