By default, IIS Express doesn't allow connections from network (only local ones), so it is not so easy to make it work.
You need to run simple proxy server on your machine, it will redirect requests from network to your local IIS Express and it will work

 - https://github.com/icflorescu/iisexpress-proxy

install it globally:
`npm install -g iisexpress-proxy`

then just need to run it:
`iiexpress-proxy {PORT} to {newPORT}`

(info taken from: https://forums.asp.net/t/2125232.aspx?Bad+Request+Invalid+Hostname+when+accessing+localhost+Web+API+or+Web+App+from+across+LAN) It worked with me.