How can I solve the problem of slow loading of QQ file transfer and video calls when using it overseas?

Many people only realize after going abroad that QQ hasn't become obsolete—old friends back home, university classmates, and clients still using QQ for communication force you to keep the software. Regarding file transfers, a friend sends you a design draft of tens of megabytes, but the transfer speed stagnates at tens of KB/s, the progress bar barely moving…