IPv6 error: "Address family not supported by protocol"

Hi all

I'm writing some scripts and have discovered that I can't get my Pro hosting account to speak to external servers. Terminal commands like wget and curl give the following error: "Address family not supported by protocol".

This is apparently a problem with IPv6, but I don't have it enabled on any of my domains in the Control Panel. I've attempted to enable it to see if that helps, but the change doesn't seem to stick (even after the "ongoing operation" appears to be finished.

Any help would be appreciated -- being able to speak to other servers is somewhat basic and necessary functionality!