I too have this exact problem. Also on DreamHost.
I too have used various other premium themes and plugins that manage to validate their license keys without error. You mentioned you’re not really a server guy, but perhaps it’s time to hire a consultant for a few days who is and can solve this persistent problem once and for all. There must be a better way to validate licenses and do auto updates because other companies have fount it.
The theme is great, but without the support to back it up it’s not worth paying an annual fee.