It looks like you are trying to connect to IPv6 and your puter
don't like it for some reason that I don't know. You could try
forcing it to connect to IPv4 by putting the IP address
(135.181.20.170) in instead of
news.eternal-september.org.
First make a note of your username and password.
Account settings -> server settings. In 'server name' replace
news.eternal-september.org with 135.181.20.170. Click OK.
When you try to open a newsgroup it will prompt you for your
username and password. Do that and check the box saying use
password manager.