In the first 40-50 minutes after I restart my server (Apache with Ngintron) I get a 403 nginx error, and in the logs it says "access forbidden by rule".
I have all my traffic redirected to HTTPS.
This is my etc/nginx/common_https.conf:

# Common definitions for HTTPS content

# TLS/SSL common
ssl_session_timeout 1d;
ssl_session_cache shared:SSL:50m;
ssl_session_tickets off;

# Diffie-Hellman parameter for DHE ciphersuites (2048 bits)
ssl_dhparam /etc/ssl/certs/dhparam.pem;

# --- Protocols & Ciphers [start] ---

# Maximum client support [enabled by default]
# Supports Firefox 1, Android 2.3, Chrome 1, Edge 12, IE8 on Windows XP, Java 6, OpenSSL 0.9.8, Opera 5 & Safari 1
ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;
ssl_ciphers / removed /;
ssl_prefer_server_ciphers on;

# Intermediate client support [disabled by default]
# Supports Firefox 27, Android 4.4.2, Chrome 31, Edge, IE 11 on Windows 7, Java 8u31, OpenSSL 1.0.1, Opera 20 & Safari 9
#ssl_protocols TLSv1.2 TLSv1.3;
#ssl_ciphers /removed/;
#ssl_prefer_server_ciphers off;

# Modern client support [disabled by default]
# Supports Firefox 63, Android 10.0, Chrome 70, Edge 75, Java 11, OpenSSL 1.1.1, Opera 57 & Safari 12.1
#ssl_protocols TLSv1.3;
#ssl_prefer_server_ciphers off;

# --- Protocols & Ciphers [finish] ---

# Set the port for HTTPS proxying
set $PROXY_TO_PORT 443;

# Include common definitions and rules with HTTP
include common_http.conf;

Could be the problem this rule: ssl_session_cache shared:SSL:50m; ?

And this is my etc/nginx/common_http.conf:

# Common definitions for HTTP content

# Initialize important variables
set $CACHE_BYPASS_FOR_DYNAMIC 0;
set $CACHE_BYPASS_FOR_STATIC 0;
set $PROXY_DOMAIN_OR_IP $host;
set $PROXY_FORWARDED_HOST $host;
set $PROXY_SCHEME $scheme;
set $SITE_URI "$host$request_uri";

# Generic query string to request a page bypassing Nginx's caching entirely for both dynamic & static content
if ($query_string ~* "nocache") {
set $CACHE_BYPASS_FOR_DYNAMIC 1;
set $CACHE_BYPASS_FOR_STATIC 1;
}

# Proxy requests to "localhost"
if ($host ~* "localhost") {
set $PROXY_DOMAIN_OR_IP "127.0.0.1";
}

# Disable caching for cPanel specific subdomains
if ($host ~* "^(webmail|cpanel|whm|webdisk|cpcalendars|cpcontacts)\.") {
set $CACHE_BYPASS_FOR_DYNAMIC 1;
set $CACHE_BYPASS_FOR_STATIC 1;
}

# Fix Horde webmail forwarding
if ($host ~* "^webmail\.") {
set $PROXY_FORWARDED_HOST '';
}

# Set custom rules like domain/IP exclusions or redirects here
include custom_rules;

location / {
try_files $uri $uri/ u/backend;
}

location u/backend {
include proxy_params_common;
# === MICRO CACHING ===
# Comment the following line to disable 1 second micro-caching for dynamic HTML content
include proxy_params_dynamic;
}

# Enable browser cache for static content files (TTL is 1 hour)
location ~* \.(?:json|xml|rss|atom)$ {
include proxy_params_common;
include proxy_params_static;
expires 1h;
}

# Enable browser cache for CSS / JS (TTL is 30 days)
location ~* \.(?:css|js)$ {
include proxy_params_common;
include proxy_params_static;
expires 30d;
}

# Enable browser cache for images (TTL is 60 days)
location ~* \.(?:ico|jpg|jpeg|gif|png|webp)$ {
include proxy_params_common;
include proxy_params_static;
expires 60d;
}

# Enable browser cache for archives, documents & media files (TTL is 60 days)
location ~* \.(?:3gp|7z|avi|bmp|bz2|csv|divx|doc|docx|eot|exe|flac|flv|gz|less|mid|midi|mka|mkv|mov|mp3|mp4|mpeg|mpg|odp|ods|odt|ogg|ogm|ogv|opus|pdf|ppt|pptx|rar|rtf|swf|tar|tbz|tgz|tiff|txz|wav|webm|wma|wmv|xls|xlsx|xz|zip)$ {
set $CACHE_BYPASS_FOR_STATIC 1;
include proxy_params_common;
include proxy_params_static;
expires 60d;
}

# Enable browser cache for fonts & fix u/font-face cross-domain restriction (TTL is 60 days)
location ~* \.(eot|ttf|otf|woff|woff2|svg|svgz)$ {
include proxy_params_common;
include proxy_params_static;
expires 60d;
}

# Prevent logging of favicon and robot request errors
location = /favicon.ico {
include proxy_params_common;
include proxy_params_static;
expires 60d;
log_not_found off;
}

location = /robots.txt {
include proxy_params_common;
include proxy_params_static;
expires 1d;
log_not_found off;
}

# Deny access to files like .htaccess or .htpasswd
location ~ /\.ht {
deny all;
}


How do I troubleshoot further exactly which rule causes the issue?