From this Microsoft article :
When an 802.11 wireless network adapter that is set to use power save
mode wants to enter a sleep state, the adapter indicates this
intention to the wireless AP. The adapter does this by setting the
power save option in its packets or in the 802.11 frames that it sends
to the wireless AP. In this scenario, the following behavior should
- When the wireless AP receives the frames that have the power save
option set, the wireless AP determines that the client network
adapter that sent the frames wants to enter a power saving state.
- The wireless AP then buffers packets that are destined for the
client network adapter.
- When the radio of the client network adapter turns on, the client
network adapter then communicates with the AP to retrieve the
This behavior enables the wireless network adapter to use less power
and to wake up periodically at the correct time to receive network
traffic from the AP.
If the wireless AP does not support this feature correctly, the
wireless AP continues to send packets to the client network adapter
even if the client network adapter radio is turned off. Therefore,
these packets are lost. In this scenario, the symptoms that you
experience may vary depending on the phase of the wireless connection
in which these packets are lost.
In short, this setting affects how long the wireless network card will sleep, and will force the router to
accumulate packets until the client wakes up or the internal memory buffer runs out and packets are lost.
The router needs to support this mechanism, which is not really guaranteed for low settings.
More info from the above article :
The default power plan that Windows Vista and Windows 7 uses for a
mobile PC is the Balanced power plan. The following is true for mobile
PCs that are configured to use the Balanced power plan:
- When the mobile PC is plugged into a power source, the wireless network adapter is configured to use Maximum Performance mode. This turns off 802.11 power save mode.
- When the mobile PC is running on battery power, the wireless network adapter is configured to use Medium Power Save mode. This uses the 802.11 power save mode.
Conclusion: The problems you are facing are because your router does not support (or does not support
well) power saving when the client is on battery and uses Medium Power Save mode
(or has monkeyed with these parameters).
Evidently, 10-20 seconds are enough to overload the internal memory buffer
of the router and cause dropped packets. The solution depends on the router, if additional memory
can be added, or some parameters for the memory stack need to be changed, or a new router is required.
Or on the client side the Power Options need changing to a higher setting to reduce the sleep period.
In any case, it seems that your router cannot be used when the clients are in power-save mode without some modifications.