Check if you don't have a VPN or something like this messing with your connection. Also, check Jenkins DNS configurations (try to start it with "--dns 18.104.22.168".
You have a different solution? A short tip here would help you and many other users who saw this issue last week.
- java.net.UnknownHostException: blabla.bla at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) at java.net.Socket.connect(Socket.java:589)