Microsoft has received negative feedback related to connectivity problems involving public WiFi hotspots connections while running Windows Vista Beta. Failed and poor connection performance as well as low throughput were also connected with using the computer on battery power. The problems were generated by the incompatibility between access point or router hardware and the 802.11 power save protocol.

"On all Windows Vista systems, the default power plan is Balanced, and pre-release versions of Windows Vista enabled Medium Power Savings for the 802.11 wireless adapter when the computer is on battery power. When the computer is on AC power, Maximum Performance (no power savings) is enabled for the 802.11 wireless adapter. This explains why connecting to AC power solves the connectivity issue for many users, as did changing the power plan to High Performance or changing the wireless adapter power setting to Maximum Performance in Power Options," explained Jason Leznek, Microsoft Senior Product Manager.

Consequently, Microsoft modified the default power setting for 802.11 wireless adapters from Balanced to Maximum Performance. But the issues are in fact related to prioritizing battery life over functionality. And there is an intimate dependency between the power savings scheme for 802.11 wireless adapters and the access point.

"When power save mode is enabled for an 802.11 wireless network adapter, the adapter periodically enters a low-power state where the radio transmitter and receiver are in "sleep" mode. The wireless adapter in the computer (client adapter) indicates the "sleep" mode by setting the power save option in its packets or 802.11 frames sent to the access point," added Leznek.

The power save options determine the access point to debut buffering packets while the adapter is asleep and only temporarily wakes up to receive the buffered packets.

As the default power saving setting for the 802.11 wireless adapter is now Maximum Performance, you can switch it back:

Change the wireless power saving setting:
- Open Power Options in Control Panel
- Choose Change Settings for the current power plan
- Choose Change Advanced Power Settings
- Expand Wireless Adapter Settings
- Expand Power Saving Mode
- Choose Maximum Power Saving, Medium Power Saving, Low Power Saving to enable various levels of 802.11 power save modes.

Choose the Power Saver power plan:
- Click on the battery meter on the desktop and choose Power Saver.
- The Power Saver plan has 802.11 power saving mode enabled for both battery and AC power.