If you’re getting “invalid argument” in irssi, it is possibly because your hostname is misconfigured.

I’m not an expert on irssi but I use it often. I think the -h flag to specify hostname (which I mistook to specity the remote hostname) somehow sets your hostname to whatever you put after it to be persistent. This problem pretty much made it so I couldn’t use irssi on this machine. The solution was very simple:

#When inside of irssi
/set -clear hostname

And you should be good.