Bridge mode disables Wi-Fi and passes those duties to your favourite wifi router. You may need to contact Shaw in order to bridge the modem for the first time. Once bridged you can turn bridging on and off through the web interface.
Fact is you may have to turn on bridging to make further changes to your modem. I did when I ran into some redundant Wi-Fi band (ssid) naming issues.
The Arris XB6 Wi-Fi capabilities didn’t hold a candle to AirPort Extreme which had three times the throuput and range of the XB6. The modem part seems to work fine.