This paper shows current problems in IPv6 technology implementations and their solutions, using a Universal-Plug-and-Play (UPnP) case study. The motivation for this work was a real difficulty found using UPnP over IPv4 to access devices from one home from another home (using private IPv4 addresses for UPnP devices), solved elegantly in theory using IPv6. For this purpose, a local environment was set up working with IPv6. Numerous difficulties have been found during this study, although the migration from IPv4 to IPv6 should have been transparent at the application layer under any platform. This paper highlights first of all the issues in the configuration of the complete all-IPv6 environment, and then it shows a solution to different problems in an UPnP implementation. As a result of the work, we have developed the first open-source implementation of the UPnP audiovisual architecture (in Java over Linux) that works correctly in an all-IPv6 network.