HexChat can be configured either with the GUI (recommended) or by editing config files.

Important: Hexchat has logging enabled by default. Please consider turning it off in the menu Settings → Preferences → Chatting → Logging

• First add a network
• name it
• and then click the Edit button to configure the details:

• set the server to irc.darkfasel.net/9999
• set Use SSL for all the servers
• unset to Accept invalid SSL certificates. If you cannot connect without this setting, please ask in the #darkfasel channel.

Optional: If you don't want to use the graphical user interface, add these lines to your ~/.config/hexchat/servlist.conf

N=Darkfasel
E=UTF-8 (Unicode)
F=87
D=0
S=irc.darkfasel.net/6697