TUN inbound: Ignore dns IPv6 setup error when neither gateway nor autoSystemRoutingTable has an IPv6 entry on Windows (#7325)

https://github.com/XTLS/Xray-core/pull/7325#issuecomment-6619158295

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Co-authored-by: patterniha <71074308+patterniha@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

proxy/tun/tun_windows.go

@@ -201,6 +201,12 @@ startOver:
 		}
 		err = t.luid.SetDNS(family, dns, nil)
 		if err != nil {
+			// Skip IPv6 the config does not ask for also when setting its DNS
+			// servers fails, as reported on Windows 11 24H2 with IPv6 disabled
+			// (Access is denied).
+			if family == windows.AF_INET6 && !address6 && !route6 {
+				continue
+			}
 			firstErr = errors.New("unable to set DNS").Base(err)
 			if err == windows.ERROR_NOT_FOUND {
 				goto startOver