This in addition to UAR or UAR+ is absolutely superb! This is required for proxy commands when the server is rebooting. Works great! You need a plugin that has alert command or other type of broadcast command that goes to all end servers. The proxy feature in your end servers will then be able to tell everyone in other servers that a reboot is happening.

I enjoy knowing that a server is about to reboot so I don't move to it until the Online message comes up.