Why does Microsoft Edge open some local websites, but not others, where the domain name is routed to 127.0.0.1 in hosts file
Like a lot of programmers, I test sites locally.
I use the hosts file to map domain names to my local ip (127.0.0.1).
I use qualified domain names, usually with a "d" subdomain (for "development").
For example:
d.somewebsite.com
d.anotherwebsite.com
and so on...
In Microsoft edge, most of the web sites work. However, a couple of them do not. There is nothing special or weird about the domain names that won't work. Just a simple d.someletters.com.
They work fine in Chrome, IE, and Firefox.
In Edge, I get the error message: "Hmm, we can't reach this page."
At first I thought it wasn't resolving the IP. However, I realized when I made a typo on another non-related url, that requests which are not routed by the hosts file are sent to my ISP to be resolved. If my ISP can't resolve it, they send back this special search results page with suggestions of what you might be trying to find. Well, when I go to my local domain, I do not get this page from my ISP. I get the error mentioned above straight from edge.
So, it seems to me that Edge is resolving the domain correctly, otherwise it would have been sent off to my ISP's DNS.
So, I would think then that maybe Edge just can't connect to the local machine. But like I said, several of these local domains are working fine. Also, using 127.0.0.1 directly in Edge also works. It's just these couple of domain names giving me a problem. And only in Edge (all other browsers work) Any ideas?
The web server is Apache2 for Windows (xampp) if that matters.
Also, if I open the debug window in Edge and monitor the network, I do not see any requests going out at all.
EDIT: I am no longer using the hosts file. I have dnsmasq running on one of my Linux boxes and I am using it for DNS instead of hosts. Also no longer using loopback (obviously since DNS is on another box now), I am using an internal private ip address (192.168...). Same issue.
Answer
Your network can block loopback as a security measure in Windows 10.
Open a command prompt as administrator, and run this to exempt Edge from a loopback:
CheckNetIsolation LoopbackExempt -a -n="Microsoft.MicrosoftEdge_8wekyb3d8bbwe"
(Microsoft.MicrosoftEdge_8wekyb3d8bbwe is the identifier for the Edge app)
There's a blog post here giving more detail: https://blogs.msdn.microsoft.com/msgulfcommunity/2015/07/01/how-to-debug-localhost-on-microsoft-edge/