Train from Hanoi Vietnam to Hong Kong

Hello, I would like to know if it would be possible to take a train from Vietnam to Hong Kong, which has a necessary stop in Nanning (which is in Guangxi province, outside of the 144 hour visa free zone). Is this possible

I see this footnote above which leads me to believe it is:
Note: Passengers taking international trains to / from Moscow, Ulaanbaatar, and North Korea cannot enjoy the 144h visa-free transit in Beijing-Tianjin-Hebei zone, while those takings trains to / from Hanoi and Hong Kong are eligible.