Not sure what you mean by "switching to xfinity".
I'm assuming you have a Linksys router that you are using the Linksys connect app to manage and that Comcast is your provider. My guess with this little bit of information is that the Comcast device is also set to router mode in which case you'd probably run into some tricky configuration problems. You most likely need to set the Comcast device to bridge mode so that it passes all the routing to your Linksys device.