I'm from Yongde, and I work in Cangyuan. Let me give you some advice:

First of all, there is no through train from Yongde to Cangyuan. I think you should know that you can only change trains (I have a headache, too). The recommended route: take a minibus from the German party to Mengding at the fork of the traffic police team at about noon. You can get to Cangyuan around 6 pm. This route is not very certain, mainly depending on whether the German mini-car can run in Mengding (German Party-Minglang-Zhenkang Wood Factory-Mengding), but this is the fastest and straightest route.

Secondly, it is the route I take most often: I go to the German Party first, buy the earliest bus to Mengding at the station, and then transfer to Cangyuan at Mengding. This one is a lot more detours than the last one.