You mean "establish a direct connection". A DNI is a form of control between the brain and a device. A direct connection refers to a non-wireless connection between two devices. You establish a DNI with a datajack or trodes and your commlink, cyberdeck, or RCC. You establish a direct connection by plugging one of those things into another device.
A retrans unit does nothing to establish a direct connection-- There's no way to get a wireless direct connection (as that is a kind of oxymoron in this case). The closest you can get is a Technomancer with the Skinlink echo (and that's really just replacing a wire with your own body).
You can have a drone apply a datatap to a wired system, which is also similar, but all this does is allow you to wirelessly access an otherwise inaccessible system. It does nothing to allow you to ignore the slave-master benefits (if they are applicable).