Will I need a visa for that?

Hi, I have Australian passport and will travel from HK to Guangzhou to meet up with my family. Will only stay in Guangzhou for one night before flying to Seoul the following day. Will I be able to receive a VOA for this one day stay? Likewise when travelling back, will fly Seoul to Guangzhou before catching train to HK the following day. I believe easily from the airport i will be able to get VOA. My main concern is when travelling from HK to Guangzhou by train. Thanks, Michael