<p>The MediaPortal 2 UPnP stack sometimes fails to detect UPnP devices with M-SEARCH.</p><p>The problem appears to affect some devices more than others - in particular, devices with many sub-devices and/or services - and/or network environments where many UPnP devices are present.</p><p>The cause of the problem seems to be that the stack is not capable of handling high or even moderate numbers of UDP packets simultaneously. Using Wireshark you can observe that devices are responding to the M-SEARCH query; however the corresponding packets don't always seem to propagate the stack. In other words, packets are getting lost somewhere.</p><p>This issue has been observed with CableCARD tuner support in MP1, and on occasion when testing/debugging with the MP2 Device Spy tool. There is no sure way to reproduce but some PCs/environments seem to be particularly prone to the issue. If you can find such an environment, the issue should be consistent and obvious. Simply run the device spy tool repeatedly and note that it doesn't pick up all devices consistently or in a timely fashion (ie. it falls back to NOTIFY based detection).<br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /></p><div class="jeditor-sign" style="display:none;"><br /></div>