Comcast has pushed 3 updates to my DPC3941T gateway in the last month. After each time, I completely lose connectivity and it will not come back by itself. The only way to bring it back is to unhook my router, directly connect the gateway to my PC, establish a connection again and then hook up my router again. It's a huge pain when I'm not home to do it because no one else knows what to do and if I travel we'll have no internet until I get back.
I have an Asus RT-AC68U router and the Comcast gateway is in bridge mode.