Could not connect to ****** Library

Hi

I'm at a loss and hopefully someone here can help me...

I have a rMBP running iTunes on a Time Capsule drive which houses my iTunes library. Up until this morning everything was working fine. Now suddenly my Apple TV says that it can't connect to library, I don't really understand what the problem is because it's clearly connected on some level as it recognises when home sharing is on or off from the message on the screen.

I have:

1. Turned home sharing on and off numerous times on both rMBP and Apple TV.
2. reset apple tv
3. restored apple tv
4. reset time capsule
5. reset MBP.

I've tried a different Apple TV and this says same thing, which leads me to thing it must be a problem with network or MBP.

I can however send videos to the Apple TV via Airplay on iTunes and from iPad etc.

Thanks in advance..

Rob