I have had this problem a number of times. I will be actively using the xFi app on my Samsung Galaxy S8. Thie problem typically occurs whn I go to the "network" button at the bottom. Instead of updating, I get a circle with three sequentially blinking dots. When I attempt to navigate awayy from the "network" button, the screen does not change. Within a minute or two, I lose all internet access and my Router completely resets. I am ususally offline for 5 minutes or more after this. In one instance (a few months ago) I power cycled my modem a number of times and finally I had to call Comcast for assitance and they had to reset something on their side of the network.
The next time this occurs, can you capture the date and time of the occurance and send it to me via Private Message? Please also include your account number and we can look into it.
To private message me, click on my name and then "Send a Message".