Time Capsule: Xfinity Bridge Mode Kills Internet?

If you are seeing a Double NAT error, this is simply saying that you have two devices that are both trying to act as a router for your network. Not what you want.

Since you changed the Xfinity modem/router from Bridge Mode to its normal role of a modem/router.......the device now operating as a router. And, you previously configured the TC to also act as a router. So, now you have two routers on the same network.

You only want one router on a network.....not two. If you cannot run the Xfinity modem/router in Bridge Mode......then you will need to run the TC in Bridge Mode.

In other words, if the modem/router is running in Bridge Mode as a simple modem......then you can run the TC in router mode. But, if the modem/router is operating as the network router (as it is at this time).....then you need to set up the TC in Bridge Mode.

If you want the TC to operate as your network router, then check with Xfinity about the possibility of swapping the modem/router for a simple modem. It will look something like this......with only one Ethernet port:

This is all that you need. You don't need a modem/router......since you already have a router.....the TC.

You might want to keep in mind that the primary job responsibility of the guy at the cable company is to find a way to blame the other guy when there is a problem.

The modem/router worked in Bridge Mode for a week. You did not change anything on the TC. So, what happened to the modem/router?

Did you test the modem/router when it was in Bridge Mode by connecting a computer directly to the modem/router to see if the computer can get an Internet connection that way?

If it cannot, then you cannot expect the TC to get an Internet connection. Bridge Mode simply does not work all that well or reliably on some modem/routers. My advice....if you want to run the TC as a router.....is to use a simple modem.