问题
I've searched in general, and looked at suggested responses here, so I hope this isn't immediately marked as a duplicate. So here goes.
I'm building a simple web app with an Angular server using port 3000 on my desktop. I've been testing it with the standard "localhost:3000" URL. I then wanted to make it accessible to others outside my home for testing and review. So I did the expected port forwarding in my router of port 3000 to my local machine at 10.0.0.90. I then constructed a link using my external IP (router's "WAN IP") like "[wan ip]:3000". And this has worked as expected, enabling external access as well as internal access. The only thing funny at the time was having to add "--host 0.0.0.0" to the server invocation.
But here's the problem. My original setup, where everything worked, was a Comcast modem with my router (TP-Link) hanging off of it. Recently, I switched to their Xfinity Gateway combo modem/router (Arris TG1682G). Now, I can't get to the server using the [wan ip]:3000 URL. I can't even ping that URL, they all time out. So, while on the phone with Comcast tech support, and not being able to determine why I had this problem (even after upgrading router firmware and rebooting it), I asked him to try [wan ip]:3000, and it worked! It also doesn't work from any other machines on my local network. But, when I changed my laptop wireless connection from my house Xfinity router to an external one (one of the many "xfinitywifi"s seen in a list of networks, besides numerous neighbors), it again worked! Poking around in Xfinity router admin pages, I didn't see anything that sounded like it was involved with this.
So, any idea what's going on, and how to fix? Thanks for any ideas or guidance.
回答1:
OK, I think I see what's going on. A colleague mentioned that for this to work, the router needs to support "NAT reflection/loopback". Looking at every setup page on this router, I don't see anything that sounds like that. Further searching shows a page where they state that this router does not support it. Oh well.
来源：https://stackoverflow.com/questions/49304424/how-to-connect-to-localhost-using-external-ip-address