arrival visa at Guangzhou port shenzhen port

Hi,

I'm currently holding Canada passport and have been in hong kong for the past week. I'm leaving back to Canada next week and would like a 2 day visit to Guangzhou. Would I be able to get a visa upon arrival in Guangzhou if I take the train from hung hum to Guangzhou? Or do I have to go to lo Wu port to get on arrival visa then take train to Guangzhou?

Thx