well, my question implied that you should try more than 1 network to see if this is 1 network that blocks your IP address or you have the problem with everyone.
There's lots of other networks in the serverlist. Try Libera.Chat, SwiftIRC, EFnet, etc
Also, look in options/connect/options/ports and try connecting both with/without the box checked for prioritizing ipv6.
The other settings there aren't relevant to connecting, with the possible exception that there may be some networks that won't let you connect without having identd enabled, but that generally implies going to your router config and forwarding port 59 the same way you forward your dcc-send port range