The data connection only supports one protocol at a time, so it's IPv6-only. T-Mobile provides a NAT64/DNS64 gateway which generates an IPv6 address for every

The data connection only supports one protocol at a time, so it's IPv6-only. T-Mobile provides a NAT64/DNS64 gateway which generates an IPv6 address for every domain you query. This works in most cases, unless you have an app that doesn't understand IPv6, or a site that uses raw IPv4 literals instead of DNS.