Fix UPnP IGD detection (#689)

src/upnp.cpp

@@ -82,6 +82,8 @@ static std::string_view status_string(int status) {
   case 1:
     return "Valid IGD device found"sv;
   case 2:
+    return "Valid IGD device found,  but it isn't connected"sv;
+  case 3:
     return "A UPnP device has been found,  but it wasn't recognized as an IGD"sv;
   }
 
@@ -109,7 +111,7 @@ std::unique_ptr<platf::deinit_t> start() {
   IGDdatas data;
 
   auto status = UPNP_GetValidIGD(device.get(), &urls.el, &data, lan_addr.data(), lan_addr.size());
-  if(status != 1) {
+  if(status != 1 && status != 2) {
     BOOST_LOG(error) << status_string(status);
     return nullptr;
   }