Why are websites not responding to changes?

Question

ubuntu

Good afternoon, I bought a vps hoster with ispmanager 5 from one hoster, periodically clients complain that they change something in the admin panel, but this is not displayed on the site, or for example, they added a rubric, after which I go to all the rubrics, but it is not displayed , it is visible only after a reboot.
I cleared the cache, disabled the cache on the server, there are no caching plugins. This problem may be with one client, and the other is fine. Tried with different providers, tried even through the anonymizer.
The hoster says that he does not see the problem, I no longer know what to do, who to contact. I hope for your help.

Answer 1

check caching settings in htaccess
on resources that have problems
Header set Cache-Control "max-age=2592000"
something like that

Answer 2

Similar to object cache. See if memcached / redis is there.

Answer 3

On the 14th there was a publication on Habré . Not your case?