Thanks for your relpy. My english is poor, but I will supply the basic information. I wish you can understand my idea. Thank you.
version : (the lastest version 19.1.2360)
OS : WIN10 EDUCATION 1809
security softwares: avast +360(a system aided software), I'm sure the two softwares work well together before. The network is good and fast until I updated avast to the lastest version.
Thank you again.