HI Steve - thanks for the help and for the tips. Clearly I need to do a bit of work on the GD Library on that server. It has not been in production use for a few years - thanks for catching that
I was just able to log-in! Here's what I did, I closed off Chrome, started up a new instance (from the WAN side) and then logged in. I haven't checked to confirm it but I'm thinking re-using the same Chrome browser session might have been the cause?