Good news!
I installed the new WCS 5.3.126 version using the link below, and the sfu client now works properly.
: https://docs.flashphoner.com/static/WCS53/WCS_update_to_5.3/#updating_52_to_53_or_one_53_build_to_another
Then, I reinstalled the previous version(5.2.2301), and the problem...