For more than 1 year I had issues with discovering UPnP devices in my network. Oh, they worked and could be found, only 1 system in the network was not able to discover any device. I searched Microsoft.com website, Google, Wikipedia and used several tools to solve the issue. Even the Intel UPnP tools were used to discover where the issue could be found.

after all kind of testings I only could analyze that the packages for UPnP / SSDP were sent but no reply from devices on the network. Wierd…

Today after too much hacking in the system, I decided to reinstall an image and check again. From scratch I had the same issue. WOW .. and than suddenly the solution was found.

My 2nd system (The notebook) was working wired and wireless on and off cause I use it now as a temp. machine. I discovered that when using the LAN-Cable the UPnP devices on the network were nowhere to be found anymore. When using Wireless: there they were. Damn, can it be possible? I took 1 direct cable from my wall mount (so the use of another switch was not necessary and: there were my devices again.

So after more than 1 day searching: the simple dump gigabit switch was blocking the incoming UPnP traffic .. pffff

Very wierd stuff