Reported failure reason: socket error.

I have been unable to connect for some time under an account I've heard for 10 or so years and just tried to create a new account to try to resolve the error. Port forwarding is turned on and my configuration seems to be fine. But I'm getting the error:

Login failed. Reported failure reason: socket error. Please change your login settings in the Options tab and try reconnecting.

Can someone please advise? I've seen other threads referencing this but no resolution. Thank you.

this could have a few reasons. The socket error means simply there is no interface (socket) available for SLSK to communicate with the "world" outside. What OS/SLSKqt Version are you using?
Have you tried another username/Password again? Application firewalls (like zone alarm or McAfee's HIP) could block it as well. Does the port check say OK to both ports.