IIS binding to different ports not behaving as expected

Hi,

I am trying to do what I think is simple, but it's not working as expected.

If I set 2 sites to 2 different ports, I can't access them on those ports. For example:

site1 (the defaults website) is on port 80 and "All Unassigned" ip

site2 (additional website) is on port 81 and "All Unassigned" ip

For both, hostname is left blank

Browsing to localhost takes me to the iis welcome page as expected.

However, browsing to localhost:81 refreshes the screen and also takes me to the iis welcome page.

Why doesn't localhost:81 take me to site2?

I'm looking for a way to browse to a website that doesn't have a DNS record - I only want to browse to it on my local server. This is IIS 10 on server 2022.

I've also tried using port 1999 for site2 with the same results.