You cannot synchronize a Windows Mobile-based device by using ActiveSync 4.x

You cannot synchronize a Microsoft Windows Mobile-based device by using Microsoft ActiveSync 4.x.

This problem occurs when companies enforce policies that allow only one network interface on their desktops computers. ActiveSync 4.x uses Remote Network Driver Interface Specification (RNDIS) to communicate with Windows Mobile 5.0-based devices when they are connected to desktop computers. Because the RNDIS connection comes up as a network interface, you cannot use RNDIS with Windows Mobile 5.0-based devices.

To resolve this problem, disable the Enable advanced network functionality setting on the device.

Windows Mobile-based Smartphone devices or Windows Mobile Standard devices

To disable this setting on a Windows Mobile-based Smartphone device or on a Windows Mobile Standard device, follow these steps:

1. Click Start, click Settings, click More, and then click Data Connections.
2. Click USB to PC.
   
   Note You may have to click More to view the USB to PC setting.
3. Click to clear the Enable advanced network functionality check box.

Note If you cannot locate these settings on your device, contact the mobile operator.

Windows Mobile-based Pocket PCs, Windows Mobile Professional devices, and Windows Mobile Classic devices

To disable this setting on a Windows Mobile-based Pocket PC, Pocket PC Phone Edition, on a Windows Mobile Professional device, or on a Windows Mobile Classic device, follow these steps:

1. Tap Start, tap Settings, and then tap the Connections tab.
2. Tap USB to PC, and then tap to clear the Enable advanced network functionality check box.

Note If you cannot locate these settings on your device, contact the mobile operator.

A network adapter is a piece of computer hardware that helps computers communicate in a network environment. Currently, most computers have a network interface that is built into the motherboard. An additional network adapter is not needed. RNDIS is a specification for network devices on dynamic Plug and Play I/O buses such as the universal serial bus (USB). ActiveSync 4.x uses RNDIS to communicate with Windows Mobile 5.0-based devices.