Não tenho experiência prática com este aplicativo, mas ele pretende usar dispositivos LAN UPnP e expô-los pela Internet. É chamado Servidor BubbleUPnP e parece que pode ser o que você está procurando.
BubbleUPnP Server provides new services on top of your existing UPnP/DLNA devices: secure Internet access to your UPnP/DLNA Media Servers content with BubbleUPnP for Android and foobar2000 on Windows. stream and download your music, video, photos with your Android device from a mobile or WiFi connection with optional transcoding to reduce bandwidth. no need to sync, to upload to the cloud, to register to an online service, ... You're in control! create OpenHome Media Renderers from any UPnP AV renderer (provides on-device playlist, multiple Control Point access to the same renderer). Works with BubbleUPnP for Android. fix issues of UPnP/DLNA Media Servers (discovery issues, broken data, add some audio DLNA compliance) by creating a proxy Media Server BUBBLEUPNP SERVER IS NOT AN UPNP AV MEDIA SERVER It requires at least one working UPnP AV Media Server (Windows Media Player, Twonky, Asset UPnP, ...) or Media Renderer to do something useful.
Confira a página O que é o servidor BubbleUPnP? para obter mais informações sobre seus recursos.