As announced on December 13, 2018, PTirc today closed port 6667 (plaintext).
From now on all our users should use port 6697 (SSL/TLS) to connect to the network. Here are the commands to use on most used IRC clients:
/server irc.ptirc.org +6697
If you use other types of services, such as ZNC, to connect to the network, you must notify their providers to explicitly use port 6697 or they will be unable to connect.