Problème /dev/urandom n'est pas lisible par PHP

Hello, I am new and I allow myself to send this post because I can not configure nextcloud 13 for my associative use.
Indeed, we want to install it on a mutated server LWS which we are currently using. We have created a subdomain and this works.
On the other hand we always have these errors:
/ dev / urandom is not readable by PHP, which is strongly discouraged for security reasons. You will find more information in the documentation.

PHP OPcache is not properly configured. For best performance we recommend using the following parameters in php.ini:

opcache.enable = 1
opcache.enable_cli = 1
opcache.interned_strings_buffer = 8
opcache.max_accelerated_files = 10000
opcache.memory_consumption = 128
opcache.save_comments = 1
opcache.revalidate_freq = 1

My configuration:
Nextcloud 13.0.5 (so not possible to update !!)
Hosted LWS server shared in https with let’s encrypt. and in the subdomain.
My sql database on LWS server.

I spent all weekend trying to search the forum, help and nextcloud support, but I did not find anything or understood to do to remove these errors.
I want to say that my computer level is very low, so I’m looking for a simple answer and a precise method to perform.

Do not wait for your help and thank the community in advance.

The top would be an answer in French.

I saw on a post below on the forum a person talks about adding 3 files
But I do not have any file on the ftp about it and especially not / etc / so no / php / …
The / etc / folder refers to which folder? or and commit to find it to modify it? It is not original on Nexcloud? strange…
Thank you for enlightening my lantern