pop up add for now wifi pass

This is coming up even with my browser closed.

@user_nstbi4

You would need to go into your browser and turn off the pop up advertisement settings, To turn off a pop-up blocker, access your browser’s settings, navigate to "Privacy and Security" or "Site Settings," and toggle the "Pop-ups and redirects" option to "Allowed" or uncheck "Block.

@XfinityDena​  This window is coming from your xfinity modem. It 'floats' on top of all windows. It can be closed but will reappear in less than a minute. It makes viewing anything on the web extremely frustrating as it can't be closed until it completes loading so it blocks whatever is normally being viewed.

I'm sure it has some great features but I will never find out because of this totally disruptive method of "encouraging" sales. See below for a reduced-size image of the window.

@xABD did you also attempt turning on pop up blockers to see if that solves the issue for you as well? 

I already have "popup blockers" enabled. I have "xfinity.com" specifically "Blocked".

I think this is actually a "webapp" created by xfinity. Note the "cp-webapp" part of the text at the bottom of the window. A webapp acts like a web page but without needing an actual web browser. Still, they have to be stored on the computer somewhere. If I could find that file, I could delete or remove it, but I doubt anyone on this forum will provide even a hint of where it might be stored. I may resort to Terminal which has much more powerful search capabilities.