As an experiment I tried feeding my TV's toslink output into the Transporter's optical input and expected the signal to appear at the coax digital output.
It didn't.
(It DOES appear at the analogue outputs, so it's not that the toslink input isn't working).

I had (perhaps naively) assumed that the TP would transfer any digital input signal to its digital outputs, but that seems not to be the case.
Unless there's some configuration setting I've missed. Can anyone help?