Connection type can sometimes be personal preference, but sometimes there are some factors to consider. Computer for audio is reliant on internet, so if the trainers internet speed is really good, there's not much issue. In fact thats what I use. It's come a long way in the last 10 years!
But if the internet connection speed is not up to par, landline is my favored method. Mobile phones for me are another thing that are too reliant on where you are sitting, and sometimes for me, I can stand in one spot and then not be heard 10 minutes later.
Hope this helps!
