Update
I made a video that better describes the process, https://youtu.be/5ZqDuvTqQVs
If you are using Visual Studio 2013 or above, make sure you run it as an administrator for this to work.
%USERPROFILE%\My Documents\IISExpress\config\applicationhost.config
$(solutionDir)\.vs\config\applicationhost.config
<site name="WebSite1" id="1" serverAutoStart="true">
<application path="/">
<virtualDirectory path="/" physicalPath="%IIS_SITES_HOME%\WebSite1" />
</application>
<bindings>
<binding protocol="http" bindingInformation="*:8080:localhost" />
</bindings>
</site>
Change the bindingInformation=":8080:localhost"
to bindingInformation="*:8080:*"
(the port number, 8080 in my case, will differ.)
Note: If it does not work try with bindingInformation="*:8080:
the asterix can be removed.
Then make sure your firewall is allowing incoming connections on that port. You may need to restart the system or at least Visual Studio to get IISExpress to reload the config file.
If this doesn't work, take a look at this answer: https://stackoverflow.com/a/5186680/985284