Low upload speed on all devices in different browsers

[Verkhovskyi]

Description

Upload speed is always near 1/2 - 2/3 of download speed, despite the fact that devices are capable of higher upload speeds. Down/Up tests:

 567/357 - iPhone 13 mini, Safari, WiFi6 - LibreSpeed
 453/485 - iPhone 13 mini, Safari, WiFi6 - Speedtest

 785/515 - Macbook Air M1, Safari, WiFi6 - LibreSpeed
 767/785 - Macbook Air M1, Safari, WiFi6 - Speedtest

1520/898 - Win11 VM, Edge, VirtIO - LibreSpeed (2.5G LAN connection)
 947/938 - Win11 VM, Edge, VirtIO - Speedtest (1G ISP connection)

 939/941 - Unraid, Speedtest CLI

Server

Latest docker container on Unraid 6.12.11 host

Screenshots

[SudoDios]

@Verkhovskyi
Hi.
I recommend using servers other than php to find the problem.

[Verkhovskyi]

Hi, @SudoDios!
Just tested with PHP and Rust - results are identical

[Verkhovskyi]

Forgot to mention that real upload speed from macbook to the server via wifi over ftp and smb reaches 100+ Megabytes (or Mibibytes, doesn't matter here) per second.