Issue 704710#0: *18394 upstream timed out (110: Connection timed out) while SSL handshaking to upstream

[belugaed]

Server operating system version

Ubuntu 20.04.6 LTS

Plesk version and microupdate number

Plesk Obsidian v18.0.54_build1800230824.08 os_Ubuntu 20.04

Hi,

Over the past week or so we've been getting the following errors across all our nginx sites, causing them to become unresponsive with 504 gateway timeouts. Restarting the nginx service brings them back.

We've checked that 127.0.0.1 and the server IPs are added to the Fail2Ban whitelist.

In the application firewall logs we have these errors at the same time:

failed to make connection to backend: httpd-UDS
18394 upstream timed out (110: Connection timed out) while SSL handshaking to upstream
704710#0: *18977 upstream timed out (110: Connection timed out) while connecting to upstream

nginx settings for one of the site's below. Server load is fine at the time of these errors.

We have however introduced a site that has had 386313Mb traffic in 18 days, bearing in mind the frontend is statically served externally and this just serves images and videos.... I suspect this might have an impact even from a bandwidth point of view potentially?

 

[sans]

Hello, @belugaed!

Please have a look at this answer:

Resolved - nginx Fails, Bringing Site Down

Hi, We had a client's site go down, and investigation showed the issue to be with nginx. The log showed multiple entries like this: 3619#0: *22389 upstream timed out (110: Connection timed out) while SSL handshaking to upstream To get the site back up while troubleshooting, we tried to...

talk.plesk.com

Looks like Apache cannot serve the files quickly.