ERR_CONNECTION_REFUSED on VPS?

Question

CentOS

Hey!
We use VPS CentOS 6.8 x64 from hosting Flops
Link to the site linktmp.com/3/fDrO7Z
Suddenly there was a connection error.
Yandex Browser says:

Edge says:
What could be the problem?
\\\\\\ Watched
similar errors, used advice:
1) Tried to clean the browser cache, Came from different PCs.
2) We tried to roll back a day ago - it did not help, apparently the problem appeared yesterday.
3) They asked the domain registrar - he says everything is fine, DNS is working and the domain is available.
4) They asked for hosting - they say decide for yourself. ( Hello guys from www.flops.ru ! )
5) Logs looked in /var/logs/ didn't really find anything. Who came-left the site and that's it.Maybe you didn't look there?
The error remained in place.

Answer 1

You have closed all ports except 21))
Be careful with iptables)))