Steve on 29 Jul, 2018 11:41 AM
unfortunately there are a variety of reasons why defining a key server can fail.
Is there any chance that you are using Little Snitch or any other firewall on your Mac? If so, please temporarily disable that software and retry to set a key server.
You write you already tried changing the DNS. But just in case, could you re-try to switch to 188.8.131.52 and see if that changes anything: If you are seeing the error Connection: Refused, it is possible that your nameserver is at fault. In that case, please try to change the nameserver (DNS) to 184.108.40.206 and try again.
Also, could you try to restart your mac and then set a key server.