So we've got a dozen or so Macs in the office, and a couple of the newer ones have this issue. It seems that either after a set amount of time, or if the screensaver on the mac is engaged (haven't positively diagnosed which one of these conditions is the trigger), the computer is no longer available to connect to via the network. It seems to be isolated only on the machines running Lion or Mountain Lion.
Every thing is set up properly for accessing the drop box/public folder of the computer....and it works when the computer is first started up; can access the drop box from a different location and copy or write files to that folder. Wake for WiFi access is enabled. After some time though, even though the computer is VISIBLE on the network, if you try to connect to it, it will time out and disappear from the network. On the "missing" computer, we can access the internet, but if you try to connect to another computer, all of them disappear.
Thus far, the only fix I have found is to disconnect, then reconnect to the wireless network. And since one of these computers is a macbook retina, hardwiring with ethernet is not an option.
Hi there...a friend of mine recommended that I try your site to solve a similar networking problem on my MacBook Pro with Lion.
Over the last few months I've started having trouble with my WiFi in that it will connect as usual to some memorized sites and has been super tricky or won't connect at all to others. One of the modems I've been connecting to has been a downhill slide in that I can get the connection and it won't connect to the internet...at this point the cable is also giving me the USB power overload error.
I started by just turning the wifi on and off then eventually starting to have to go through the "assist me" directions with the Network Preferences and it would create a new location. One forum suggested deleting the locations and the keychain associated with the networks I was having difficulty with which I did. The odd thing is that I even though I deleted the extra locations (besides "Automatic") they all keep showing up again in the list.
Not sure if this is a bug, corruption or if my wifi card is failing...
Any suggestions would be helpful...and for the record I'm a Mac convert and don't know too much about troubleshooting at this level.