So I allowed my subsites to use the credentials set on the network but :-->:
An error occurred with HU CEACS Portal. Please try again later.
API Error Code: 191
API Error Description: The specified URL is not owned by the application
Error Message: redirect_uri is not owned by the application.
When looking at the backend of that subsite in the facebook plugin settings is says "Look for Site URL field in the Web Site tab and enter your site URL in this field: http://xxx.main.com"
The application is developed for main.com. I assume this to be the issue but I selected the option for network to override this. It seems to be looking at the subsite url when trying to access facebook connect.
This was working fine before the recent upgrades. NJot sure which one but I just checked it on accident.
I am able to fb connect on main.com site