Who can occupy the port?

Question

Nginx

I took other people's servers for maintenance, everything was assembled on my knees, but in some places it's not bad, in some places it's so-so.
In general, as always, porridge with domain names, document roots, etc., but it seems like I figured it out.
The essence of the problem is as follows
One of the sites fell off,
I look at the nginx
proxy_pass config leads 127.0.0.1:8030
lsoft -I -P -n
does not see anything there.
FPM weighs 9000 and I can see it.
Further more than 8030, I didn’t find any mention in /etc at all (except for 1 line in nginx)

Actually, the question is
, where to look further apache
configs empty
nginx config no left upstream fpm config also does not have this port.
sinned on an external server so that there are about 30 of them
but 127.0.0 somehow hints at something else.
What ideas can be?

Answer 1

netstat -nlpwhat does it show you about this port?

Answer 2

Docker, LXD container? what is shown ip a - from the left? or is it empty?