Hello,
I agree a 100% if one reads the docs all the way and follows it by the word, “I” wouldn’t have had the issue, but:
On two machines, I tried to install NS8, it failed with error messages about wrong password, bad user … , and a service unable to start, and then I had to find out how to uninstall whatever has been installed otherwise stuck.
So I went for a minute trying to fix the wrong thing .
After setting up a real FQDN all worked fine .
My suggestion is to make the install script look for that detail explicitly,
and stop the install from the start saying for example : “please get an FQDN dude !” 
The missing FQDN can be because of a “forgetting” or simply a non “functioning” FQDN … from dns or other network issues …
Regards