connect() failed (111: Connection refused) on Nginx in front of a Node app. Where now?

after reboots and deploys, teh classic causes are a socket path mismatch (fastcgi_pass unix:/run/php/... pointing at a socket name that changed), teh app not being enabled at boot (systemctl enable yourapp), or a container listening on 127.0.0.1 inside Docker sooo teh proxy container cant reach it, bind to 0.0.0.0 in the container and use the service name in the proxy config. fingers crossed 🤞

hmmm check the app service right after a 502: systemctl status php*-fpm, systemctl status yourapp, or docker compose ps. if it shows restarts or exited state, read its own logs with journalctl -u yourapp -n 200 or docker compose logs app. The real error lives there, not in teh proxy log. lmk how it goes

have u checked your 502 settings? mine were reset after an update. came here to say exactly this

ps unrelated but anyone elses coffee machine also judging them today :)

help!! reading this at 2am instead of sleeping, no regrets im about to throw this thing out the window lol

Look for teh kernel's OOM killer: dmesg -T | grep -i -E 'killed process|out of memory'. small VPSes kill PHP-FPM workers, Node or database processes under load, which produces 502s during traffic spikes. add swap, reduce worker counts, or move to a bigger plan. fingers crossed 🤞

oh ive been there lol make a backup before u touch teh fan curve, learned that teh hard way good luck man!

wait what everyone keeps saying this but nobody posts proof but hey ymmv

have u chekced your nginx settings? mine were reset after an update

yep

hmmm exact same thing happened to my brand new build last month good luck man!

Make the app restart itself: Restart=always in the systemd unit or restart: unless-stopped in Compose. That's not a fix for the root cause, but it turns minutes of downtime into seconds while you investigate.

hmmm for PHP-FPM, check its log for server reached pm.max_children setting... when all workers are busy, new requests queue and eventually fail, tune pm.max_children based on available RAM divided by average worker memory, not by guesswork. hope that helps :)

my moms pc is officially haunted... honestly just reset the fan curve and save yourself the pain

A 502 means the proxy reached out to the app behind it and got a broken or no response, read teh proxy's error log first: sudo tail -n 100 /var/log/nginx/error.log for Nginx. connect() failed (111: Connection refused) means nothing is listening; upstream prematurely closed connection means the app crashed or killed the request mid-way.

ok update: did what @viktorz766 said and its fine now

been there man +1 same here hope that helps :)

oh ive been there lol exact same thing happened to my mac last month hope that helps :)

dumb question but how do i even check the router