Following this thread, it came out that this is a Map-Control-issue, not a StreamSocketListener -problem. So we are back in this forum.
I'm loading locally stored map-tiles from a TileSource in the Map-Control. This works fine, but not on Lumia-Phones, if there is no network connection. On Samsung Ativ S its still working. On Samsungs it was also not working before the GDR3-update. On Lumias its not working even with the Black-firmware.
Attached is a project to reproduce.
Just run the app and there should appear some red "suns" on the map, which are my locally stored tiles.
Turn off network, e.g. activate airplane-mode, run the app again and there are no "suns" anymore.
Try on a Samsung and you'll see that there are still the red suns.
I think, there must be something different in the GetUri-Overload of the Map-control on Lumias, when not connected.