I have a home server (running Ubuntu, which I named “lenovo”) that runs a couple of HTTP servers. These HTTP servers are accessible to other clients on my home LAN. They are always accessible to clients when using the static IP of the home server. They are also always accessible to clients when using the Ubuntu computer name (with .local added): “http://lenovo.local”. However, the server is not always accessible from some clients when using the local DNS name which I assigned it via my Unifi Console: I assigned the Ubuntu machine the local DNS name “lenovo.redacted.duckdns.org”. (I did this after finding advice online that said not to use “.local” and instead to use a real DNS name). I actually am using “redacted.duckdns.org” to point to my public IP — but I am using “redacted” here instead of my actual duckdns reservation, obviously.

The problem:

When trying to access “http://lenovo.redacted.duckdns.org”, it ALWAYS works when using curl on the commandline (and nslookup on the name also always works as expected). It also works on MacOS. BUT on the Windows 11 computers, and when using a web browser to view the URL, it very often results in “ERR_CONNECTION_REFUSED” (or similar — the exact error evades me as the issue is not occurring right now). Note that the issue is only seen on Windows 11 using a browser such as Chrome or Edge. On the same Windows 11 machines on the command line, it always works (curl and nslookup). In browsers on Windows, it sometimes works, and sometimes doesn’t work (as in, reloading over and over will intermittently work then not work, flapping on and off). The IP address “http://192.168.1.200” and the Ubuntu-assigned “http://lenovo.local” always work as well. It’s only the Unifi-assigned DNS name that is causing problems, and only in Windows 11 browsers (Edge and Chrome). What’s going on?

I checked windows networking, it says it is using DNS 1.1.1.1 and that it’s not encrypted. MacOS is also using the same DNS server.

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