I started getting a 502 bad gateway on odoo 14 hosted on Digital Ocean, it happens randomly, it doesnt really have any pattern at all.

it happens randomly in some machines that use the service sometimes, some other times the whole services collapses, the only solution is restarting both odoo and nginx services all over again

is worth noticing this odoo has at least 5 databases

in the nginx log im getting the following error:

2023/09/28 15:27:13 [error] 21272#21272: *3214384 connect() failed (111: Connection refused) while connecting to upstream, client: 190.97.228.2, server: sitename.com, request: "POST /longpolling/poll HTTP/1.1", upstream: "http://127.0.0.1:8072/longpolling/poll", host: "mysitename.com", referrer: "http://mysitename.com/ web"

my odoo server conf:

[options]
; This is the password that allows database operations:
admin_passwd = QSTSG7DzlrIzUT5N
http_port = 8069
logfile = /var/log/odoo/odoo-server.log
addons_path=/odoo/odoo-server/addons,/odoo/custom/addons
proxy_mode=True

my nginx default config

server {
  listen 80;

  # set proper server name after domain set
  server_name sitename.com www.mysitename.com;

  # Add Headers for odoo proxy mode
  proxy_set_header X-Forwarded-Host \$host;
  proxy_set_header X-Forwarded-For \$proxy_add_x_forwarded_for;
  proxy_set_header X-Forwarded-Proto \$scheme;
  proxy_set_header X-Real-IP \$remote_addr;
  add_header X-Frame-Options "SAMEORIGIN";
  add_header X-XSS-Protection "1; mode=block";
  proxy_set_header X-Client-IP \$remote_addr;
  proxy_set_header HTTP_X_FORWARDED_HOST \$remote_addr;

  #   odoo    log files
  access_log  /var/log/nginx/odoo-access.log;
  error_log       /var/log/nginx/odoo-error.log;

  #   increase    proxy   buffer  size
  proxy_buffers   16  64k;
  proxy_buffer_size   128k;

  proxy_read_timeout 900s;
  proxy_connect_timeout 900s;
  proxy_send_timeout 900s;

  #   force   timeouts    if  the backend dies
  proxy_next_upstream error   timeout invalid_header  http_500    http_502
  http_503;

  types {
  text/less less;
  text/scss scss;
  }

  #   enable  data    compression
  gzip    on;
  gzip_min_length 1100; gzip_buffers    4   32k;
  gzip_types  text/css text/less text/plain text/xml application/xml application/json application/javascript application/pdf image/jpeg image/png;
  gzip_vary   on;
  client_header_buffer_size 4k;
  large_client_header_buffers 4 64k;
  client_max_body_size 0;

  location / {
  proxy_pass    http://127.0.0.1:8069;
  # by default, do not forward anything
  proxy_redirect off;
  }

  location /longpolling {
  proxy_pass http://localhost:8072;
  }
  location ~* .(js|css|png|jpg|jpeg|gif|ico)$ {
  expires 2d;
  proxy_pass http://127.0.0.1:8069;
  add_header Cache-Control "public, no-transform";
  }
  # cache some static data in memory for 60mins.
  location ~ /[a-zA-Z0-9_-]*/static/ {
  proxy_cache_valid 200 302 60m;
  proxy_cache_valid 404      1m;
  proxy_buffering    on;
  expires 864000;
  proxy_pass    http://127.0.0.1:8069;
  }
  }