Use make menuconfig - or linux-menuconfig when using Buildroot - to invoke the kernel configuration wizard.

Then, enable the following modules under Device Drivers, Network device support, USB Network Adapters

• Multi-purpose USB Networking Framework
• CDC Ethernet support
• Host for RNDIS and ActiveSync devices

If the device you’re using provides an IP address using DHCP, there’s a bug in some Linux kernel versions that hinders obtaining an IP address from the device. You might want to patch or upgrade the kernel.

Update

Recent kernel versions require the following modules to be enabled

• cdc_ether
• cfg80211
• rndis_host
• rndis_wlan
• usbnet