Ionic lab through specific port

I’m building a small project using ionic and visual studio. I’m sending AJAX to a web service, and for that to work I need the ionic serve Dev server and the web service to run on the same port. I know this can be done with the command “ionic serve [http-port] [reload-port]”, but when I try to run it with --lab I get a 404(it works only on the default 8100). Is there any way to run ionic lab through different ports?