Have you tried setting the split limit in IDM to only 1? Part of the reason I think it's happening is the requests made by IDM are unique, hence Plesk is thinking it needs to create unique files based on the number of requests sent by IDM.
I'm not a WordPress expert but ran into a similar problem. It may have to do with the permalink structure and the current .htaccess / nginx rules. By the way, I've found OPCache (in PHP 7.x+) to be a lot better than other caching plugins.
On the surface, it looks like a personal preference.
wget is installed by default on ubuntu distros.
lynx is a text-based browser that has to be installed.
Personally, I would recommend wget to avoid installing extra packages, but that's just personal opinion.
So close..... Default has to be default. Thus the full command:
user@computer:~# plesk bin branding_theme -p name default -destination /tmp/default.zip
If you have access to ssh on the server and root access, you can install snmp support from this link (https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-an-snmp-daemon-and-client-on-ubuntu-14-04)
Note, I did not follow the article exactly. I created an OpenVPN...