diff -r 383005aa9cdc -r b1a1702262c9 mercurial/hgweb/server.py
--- a/mercurial/hgweb/server.py	Wed Jul 01 15:43:15 2020 +0200
+++ b/mercurial/hgweb/server.py	Fri Jul 03 23:25:19 2020 +0200
@@ -382,7 +382,7 @@
         self.errorlog = elog
 
         self.addr, self.port = self.socket.getsockname()[0:2]
-        self.fqaddr = socket.getfqdn(addr[0])
+        self.fqaddr = self.server_name
 
         self.serverheader = ui.config(b'web', b'server-header')