While we’re big fans of Yosemite, there’s one annoying bug that we’ve experienced. From time to time, our network connection simply stops responding. We’re not alone. The problem stems from a piece of the networking stack that Apple has completely rewritten.
The ‘discoveryd’ routine is used to find and connect to devices on your network. The trouble is the new routine, which replaces the older and much mature mDNSResponder service, messes up Bonjour and DNS resolution.
There’s a detailed explanation of all this over at macnn.
Suffice to say – the problem can be a significant pain – particularly if you have lots of devices on your network. In the modern home or office with printers, smart TVs, media streamers, network storage devices and more, it’s pretty easy to rack up 20 or more connected devices.
If the problem occurs, the simple cure is to restart the network connection on your device. If you’re on a Mac using Wi-Fi, simply turning the Wi-Fi off and on usually fixes the problem for us. When web browsing, restarting Safari usually does the trick as well.
On our Apple TV, restarting the device gets the network connection humming again.
Ars Technica has detailed a process for installing mDNSresponder again, although it doesn’t always work and running older software like this is totally unsupported and might break other applications.