Hi Johny have you resolved this? I just caught your post looking for something else today. If you have NOT resolved it, it's highly likely this is a NETWORKING issue and is simple to resolve.
Look first in the diagnostic logs by launching /applications/utilities/console.app and look for SYSTEM LOGs in the side bar of the UI. If the problem is persistent there will be some messages in here.
SELECTIVELY post these in this thread. Please don't flood it with any lines of noise. Try and be selective (surgical) of your error messages.
I'm sure others reading this post will also help you get this working.
Post your results for others to see.