¿How to improve and max upload speed?

Hi, using Nextcloud I can see that uploading a single file only uses 8 mbps, but uploading multiple files could max the internet speed of 50 mbps, how could max the upload speed for a single file upload? Checking if it was my browser and repeating the test with G Drive it gets 46 mbps for 1 file upload, and Dropbox gets 18 mbps for single file upload, I think there should be something to improve the 8 mbps single file upload speed to Netcloud in the browser. Thanks in advance.

Nextcloud 16.0.6
Ubuntu 18.04
Apache 2.4.29)_:
PHP version (eg, 7.2.24):