Why might net::ERR_CONNECTION_RESET fail?

Question

PHP

In general, 2 projects are locally deployed, on one front, on the other back (API).
Front in English, back in yii2. The server is apache.

The problem is this:
Sometimes the front, sending prefly requests to the back, receives a net::ERR_CONNECTION_RESET error in response and, of course, an error falls, for a promise that received nothing for further fetch. BUT , literally a second after the request (OPTIONS) failed, he sends it again and everything is successful.

The problem is given only in Google Chrome (well, Yandex browser), not in Mozilla (it seems to be waiting for an answer).
CORS is configured.

The logs are also empty (APACHE-err/Apache-query).

Here is how it looks in general in the network: