What are the dimensions of the image?
Does the issue occur with:
1). All plugins disabled? (if not, enable them)
2). Temporarily changing to a different theme?
At this juncture it sounds like the issue is coming from a code level issue rather than the server itself.
Is the Nginx open files limit to updated to match?
/etc/nginx/nginx.conf
worker_rlimit_nofile {value of the OS hard limit}
# sudo systemctl restart nginx
There threads about this here and there such this one but thus far as Google hasn't taken action, we've just blocked the entire 34.174.0.0/16 for now as the attacks were become relentless. If you're using CloudFlare, then you can do this via a rule in CloudFlare versus trying to block it in Nginx.
While there is a procedure to update existing Apache and Nginux values set via Plesk as documented here, it would be quite benefiicial to simply add a checkbox to each of those textarea inputs to "Override existing values" which would then loop through and apply those to existing sites.
It...
For a limited number of top IPs, the reverse lookups should be relatively quick and the real benefit to the service provider view would be quickly identifying potential sources of abusive traffic. CloudFlare and other products do a very good job of providing "At a glance" type dashboards like this.
Instead of relying on Linux commands, it might be helpful to add these to the home dashboard and/or the health screen, and even more so with corresponding reverse lookups!
Top external addresses with open connections:
# netstat -nt | awk '/^tcp/ {print $5}' | awk -F: '{print $1}' | sort | uniq...
Just to clarify, this is not about copying plugins but rather replacing a plugin that is already installed. For example, if you had a custom plugin that you wanted to update en mass or if you wanted to deploy a hotfix for an existing plugin that isn't yet available from a repository.
While not a feature currently present, it would be handy to be able to replace a manually added plugin via the Toolkit GUI instead of having to upload it as a brand new one and then have to manually add sites to it.
Funny you should ask...
Question - Try our new tool to upgrade your old MariaDB server from Plesk UI
Make sure to take a full backup of your server before running that tool!
So the database sounds like it's being stopped (but not gracefully) since you noted that you have to start the service up again and there are no logs about shutdown. Check the messages log and you might find that it's being sacrificed by the OOM killer.