Hi Anna,
The internet sometimes seems to function a bit differently inside China. Where are you currently hosting your DTM library for the ch directory? If it is outside of China, I'd recommend hosting it inside China. This will ensure you don't have to worry about the Chinese firewall issues we sometimes see from customers. Depending on how your DTM library is setup currently, this might mean you need to create a new DTM property.
For example, if you are currently using Akamai hosting, you'll likely need to change to self-host since I don't believe Akamai has an edge inside China. Then you could use your own method for deploying the library inside of China. If you'd rather continue using Akamai for the rest of your sites, you'd want to create a new property.
Please let me know if you have questions.
Thank you,
Jantzen