webdav upload is slower than download in intranet

intranet
server: apache httpd 2.4.41, default config, win10, 1.0Gbits LAN
client: winscp 5.15.5, default config, win10, 5g wifi at 866Mbps
protocol: webdav, https
download file from server: 25MB/s
upload file to server: 12MB/s
Upload is much slower than download, why?

PS:
Same server , network, protocol
client: ES file manager, Android phone P20Pro, 5g wifi at 866Mbps
download file from server: 60MB/s
upload file to server: 10MB/s

So do I understand correctly that you get slower uploads in other WebDAV clients too?

martin wrote:

So do I understand correctly that you get slower uploads in other WebDAV clients too?

Yes.
No upload rate limit has been set in apache.
As I know, winscp supports multi-thread download.
Dose winscp support multi-thread upload?
Dose webdav protocol support multi-thread upload?

nde wrote:

As I know, winscp supports multi-thread download.
Dose winscp support multi-thread upload?

What do you mean by "multi-thread download/upload"? WinSCP supports downloading and uploading multiple files in parallel from and to a server (using any protocol).

martin wrote:

nde wrote:

As I know, winscp supports multi-thread download.
Dose winscp support multi-thread upload?

What do you mean by "multi-thread download/upload"? WinSCP supports downloading and uploading multiple files in parallel from and to a server (using any protocol).

There is an option "multiple connections for single transfer". Dose it mean download/upload one file using several connections?

nde wrote:

There is an option "multiple connections for single transfer". Dose it mean download/upload one file using several connections?

No. That is not supported:
https://winscp.net/tracker/513