I want to travel over lang from Hong Kong to China via Nanning, what kind of visa do I need?

So you just transit in Nanning? If so, how long is your transit? If it is less than 24 hours, then you needn't apply for anything. If it is longer than 24 hours, you should apply for a transit type from Chinese embassy in your country in advance.

Hey I actually meant from Hong Kong to Hanoi via Nanning. Sorry for the confusion. I already decided to take a flight tomorrow to Da Nang because 2 days ago I went to the China Travel Services and I was told I need a visa if I want to travel through Nanning. Due to a public holiday there was only one visa center on the other side of the city open. When we arrived there we got an employee who could speak even less English. She told us we needed a visa for Nanning even tho I tried to explain we would only be passing through. I knew she was not fully understanding our story but she kept on saying we need a visa and due to public holidays in China it would not be ready until April 13th. Since we were not planning on staying this long in Hong Kong we decided to book a flight to Vietnam. I still don't know whether you are allowed to be in China when you travel over land if you leave the country withthin 24 hours. I could only find information about this concerning airports/flights. Could someone clarify this for the next traveller who wants to travel from Hong Kong to Vietnam?