Learn Turkish: Sistem kapanmak üzere çünkü sunucu cevap vermiyor. - The system is about to shut down because the server is not responding.

It uses the full infinitive verb kapanmak (to shut down) followed directly by the word üzere. The structure [Infinitive] + üzere is the standard way in Turkish to express that an action is on the verge of happening or "about to" happen.

Why is the verb kapanmak used here instead of kapatmak?

Kapatmak is transitive, meaning "to close [something]" or "to turn [something] off". By adding the -n suffix, it becomes the intransitive or reflexive verb kapanmak, meaning "to close" or "to shut down" on its own. Since the system is shutting down automatically and not actively turning something else off, we use kapanmak.

Shouldn't there be a "to be" suffix at the end of the first clause, like kapanmak üzeredir?

You can certainly say kapanmak üzeredir, using the third-person "is" suffix -dir. However, in everyday spoken and written Turkish, the -dir suffix is frequently dropped when the subject is "he", "she", or "it". Ending the clause with just kapanmak üzere is grammatically complete and perfectly natural.

Where does the word sunucu (server) come from?

It comes from the verb sunmak, which means "to present", "to offer", or "to serve". The -ucu suffix is added to create a noun for the "doer" of the action. While it means a computer "server" in IT contexts, it is also the standard word for a TV or radio "presenter" or "host".