Samsung
Set Up Private DNS auf Samsung
Private DNS on Samsung devices replaces the DNS server given out by your mobile carrier or Wi-Fi router with an encrypted connection to a provider of your choice. This can speed up website lookups and stop your network operator from seeing which domains you visit.
The feature lives inside the connection settings, not the general Wi-Fi menu, which is why most people never find it. Go to Settings ➤ Connections ➤ More connection settings ➤ Private DNS.
You get three choices. Off disables private DNS entirely and falls back to whatever the network provides. Automatic lets Samsung One UI pick a working configuration if one is available. Private DNS provider hostname lets you enter a specific hostname, then tap Save to apply it.
If your phone suddenly loses internet access after switching networks, a strict provider hostname is usually the cause: some corporate or public Wi-Fi networks block encrypted DNS traffic outright. Switching back to Automatic or Off restores the connection immediately. On rooted or custom firmware devices this setting can behave differently, so a factory Samsung device with One UI gives the most predictable results.