Answer
IEE's built-in internal browser (used specifically for links opened from within the client, like Streams notification links) is a lightweight, embedded version of Internet Explorer, hardcoded into the client itself — this isn't configurable or changeable through any setting. Since IE isn't a supported browser for the modern web pages/Aurena pages these links often point to, the practical fix is to make sure the link/notification is configured to open in an external browser instead of relying on IEE's own internal one.