Why is there sometimes quality differences between Wi-Fi networks and cellular data networks?

Samsung Device

A small number of users may have network configurations that do not work well on IPv6 networks. In many cases, these configurations do not cause problems on Wi-Fi networks because these networks typically still use IPv4. However, issues may occur when the device switches to an IPv6 network, such as a mobile carrier's data network. The primary cause of issues on IPv6 networks is the use of VPN solutions that only support IPv4.

Samsung and many VPN client vendors will eventually release software updates to improve IPv6 support. In the meantime, temporarily forcing IPv4 use over mobile networks will restore expected behavior. Samsung recommends reverting these changes as soon as IPv6 is fully supported by your device, VPN client, and VPN backend software.

The following steps force an IPv4 APN to be used for mobile data connections. The APN protocol must be manually set to IPv4 on each device:
  1. Go to Settings > Mobile Networks (With some carrier models and earlier Android versions, you might need to select Settings > More Networks or Connections > Mobile Networks)
  2. Verify that Mobile Data has been selected
  3. Select Access Point Names and tap the + icon on the top right to add a new APN
  4. Copy the configuration of your existing carrier APN but set the APN Protocol value to IPv4.