Trouble playing streaming video on NextCloud?

Question

Web servers

Good afternoon/evening
The problem with playing streaming video in NextCloud, if the file is more than 500 mb. There is no video image, but the sound goes on. Video files smaller than 500 play without problems.
When testing, there is one caveat: this problem is in all browsers and on desktops and mobile devices, except for MS Edge in W10.
The system is deployed on Ubuntu 18; on a physical machine with 4 cores, 4 GB of RAM and 4 GB of swap file; internet channel 30 mb. Nothing is deployed other than NextCloud. According to monitoring, the system load is minimal.
Thank you.

Answer 1

and in the logs of the NC itself there is no information? Or in the system that there are not enough resources?
under php I have allocated more than by default and tuned php-fpm