I've recently bought an arduino yun, i have followed the arduino's guide in order to connect it to my wifi.
I managed to connect the yun and i was able to get to dariushyun.local (i changed the name of arduino.local) but the next day the yun didn't connect to the wifi and i wasn't able anymore to get to dariushyun.local, i tried the httpclient example but obviously it didn't work but the wifistatus example worked because it said that yun was connected to my wifi with a signal of 70%.
So i used the ethernet cable but sometimes it works other times doesn't.
I gave my Yun connected to my existing wifi router a fixed IP. I just use the IP. The "name" of the Yun never seems to work for me. If you can I would recommend using static IP or having the DHCP assign a static IP to the Yun. Then use the IP.