Macbook and iMac not communicating/sharing files. Not changed settings.

Hello chaps!

My partner and I run our businesses from our home office. He has an iMac and I have a Macbook. We connect to the internet wirelessly.

Until recently our Mac's shared files wirelessly without us doing anything. His iMac appeared in my Finder browser and vice versa.

Then one day this stopped, I cannot find the iMac and he cant find my Macbook. We can find each others Mac via bluetooth but only the Macbook can access the files. We hadnt changed any of our settings.

Here are my (Mabook) sharing preferences if that helps, the iMac's are the same:

Can anyone help because its a pain in the backside! We are having to do everything over email and that takes up a load of our ownload limit.

Any help or advice would be greatly appreciated!

Thanks

Laura x