Uno de los problemas típicos es insuficientes workers. En una maquina con nginx nos sale lo siguiente en los logs:

2025/01/09 18:31:53 [warn] 2214964#2214964: 1024 worker_connections are not enough, reusing connections
2025/01/09 18:31:54 [warn] 2214964#2214964: 1024 worker_connections are not enough, reusing connections
2025/01/09 18:33:59 [warn] 2214964#2214964: 1024 worker_connections are not enough, reusing connections
2025/01/09 18:34:01 [warn] 2214964#2214964: 1024 worker_connections are not enough, reusing connections
2025/01/09 18:34:04 [warn] 2214964#2214964: 1024 worker_connections are not enough, reusing connections
2025/01/09 18:34:07 [warn] 2214964#2214964: 1024 worker_connections are not enough, reusing connections

Lo primero es conectarnos por ssh y hacer una copia de la config de nginx

cp -v /etc/nginx/nginx.conf /etc/nginx/nginx.conf.fresh.backup

Luego revisamos la cantidad actual de workers

grep worker_connection /etc/nginx/nginx.conf
y nos da:
worker_connections 1024;

Editamos ese valor de 1024 por el que queramos y salvamos.

nano /etc/nginx/nginx.conf

Comprobamos que lo hayamos hecho bien

nginx -t 
y nos debería salir algo como:
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful

Y si esta todo bien, cargamos la nueva config:

/scripts/restartsrv_nginx