EOF on Socket, Sign-in attempt prevented

EOF on Socket, Sign-in attempt prevented

Trying to set up Google Apps account with Zoho Enterprise. There are zero relevant instructions anywhere on the Zoho site or in this forum after a dozen different searches.
I'm in a circle of EOF on Socket errors followed by Auth error messages that appear to be from Google together with a link to a page that is entirely unhelpful.
There seem to be multiple threads under "EOF on Socket" erros - is it too much to ask that Zoho actually sets up a Help page that actually addresses the issue?
And how do I solve this? Anyone?