Client Macs lose connection to server after Sleep

Ok, so my previous issues with disk I/O erroros with contacts/Mail etc appears to be resolved after I re-installed ML Server and ML clients on all my macs -- not entirely sure why but now I have new problem where client macs lose connection to the server after sleep

So my current setup is as follows:

Server Mac

Mac Mini Server running ML 10.8.2 Server

Client Macs

2 x MBAs with 10.8.2 (Core2Duo & iCore5)

1 x Mac Mini running 10.8.2 (Core2Due, 4GB 2.4 Ghz etc)

Issue:

If I leave the client Mini logged in say, as me and either the mini goes to sleep (or if I put it to sleep) and then I wake the mini up, I appear to lose connection to the server - so whilst I am still logged in as me, I've lost my connection to my home directory e.g. Doc/Music/Pics (I can see instantly my desktop picture defaults to ML galaxy picture, opposed to something I've chosen) folders are no longer present. So obviously as mailbox,iphoto & itunes libraries are missing, Mail, iPhoto & iTunes fail to operate and I my only course of action is to log out and log back in and everything is fine.

I get the same issue - although not as frequent - on MBA's when you close it and results in having to log out and in again to resolve the issue. I also saw the same problem when it was running Lion as well.

A couple of things to note:

- Server Mini is never asleep and is running 24x7 (as its a media streamer as well)

- Its only occured when in deep sleep - so if I wake the mac up after a few seconds of sleep, its just fine but if say I leave it overnight and wake it in the morning, its no longer connected.

Any pointers will be welcome and given that it appear to have occured on a client Mac with Lion as well, it would imply its an issue with the server rather the individual client Macs. Also note, I don;t recall the problem when running Lion Server.

Thanks

Rob