Sonos conflict 802.11n router mode 300 Mbps

I'm a happy Sonos user. Yet room for improvement.

I notice that Sonos doesn't communicate properly with my ASUS RT-56U router when configured at high speed (Auto or N) mode, meaning 802.11n mode or max throughput at 300Mbps.

Radio goes well but Music Library songs sound distorted.

I'm therefore forced to limit the ASUS speed by choosing b/g mode only, which caps my WIFI network speed to 54Mbps.

Anybody who knows a workaround?

-setup: Sonos Bridge wired to ASUS