DNS
What it is: DNS converts domain names into network addresses. The result affects subsequent domain rules, address rules, and connection targets. DNS issues may appear as inaccessible domains, timeouts for some requests, or different results for the same address on different networks.
Where and how to configure it: Open the DNS-related options from Settings, and also check whether the General section of the current Config contains DNS settings. Prefer one clearly defined, explainable source rather than layering multiple conflicting resolution settings. After changing it, test both domain access and direct-address connectivity.
What to watch for: If Direct works but Config fails, or the server test succeeds while domain access fails, focus on the relationship between DNS and the rules. If results differ between Wi-Fi and cellular data, record the resolution behavior on each network before drawing conclusions.