I strongly recommend
For these last weeks (may, June 2023) I traveled alone in China. I strongly recommend to go through the Travel China Guide Tours internet site to book your train e-ticket. It is the easiest and fastest way to do it. If you have any problems you can contact them, they speak English, they are understanding. With them you can easily change or cancel your bookings. Thanks to them my trip was easy to organise day to day.