This object sets the advertised lifetime, in seconds, that the switch tells UPnP control points to expect between SSDP advertisements, and if a control point doesn't hear a refresh within this window it assumes the switch is gone, so the switch itself actually re-sends advertisements more often, at roughly half this duration minus 30 seconds, to stay safely within that window despite UDP's unreliability. An admin lowers this value for control points to detect the switch's disappearance faster, or raises it to reduce SSDP traffic on the network. For example, setting me1200UpnpConfigGlobalsAdvertisingDuration to 1800, 30 minutes, tells control points to expect a refresh at least every 30 minutes, while the switch itself resends roughly every 870 seconds to stay within that window.