My server shows an error of "Please using S(tream) mode", but I don't know how to?

[L] Mode Z
[L] 504 Please use S(tream) mode

How to solve this problem?

This problem is caused from that your server does not support the compression mode (Mode Z), hence the transfer compression should be closed. You can disable the transfer compression at (Sites -> Site Manager -> Options -> Data Compression (Mode Z)).