Issues with iMac on local network

Question

My iMac has started to disappear from my local network and I cannot find the source of the problem. The iMac remains connected to the internet and browsing works fine. Everything appears to be operating as normal from the iMac. Unfortunately Any apps on my iPad however cannot see the iMac and I cannot access Shared hard drive data. Additional home sharing on my iTunes goes down.  This is reproduced on every app I try. (Mainly Air Video and Splashpad)
This problem is intermittent and I cannot resolve it through restarting the iMac or playing with network settings. Turning the iMac off for several hours usually resolves the problem. Occasionally however the problem will resolve itself without warning and everything will connect as they should.
Any assistance in helping me understand this problem and any fixes would be gratefully received.

Answer 1

A couple of things i'd do at this point is to remove all your networks from the preferred network list, then re-add your wi-fi. If that doesn't fix it, i'd do a pram reset. Another couple of troubleshooting steps is to try it in another user and see if it still acts up. Also, try it in safe mode. I do understand that it's intermittent, so some of these steps might take a while to see if it's recreated the issue. Another thing, have you restarted the router?