YouTube "Connection to server lost" on WiFi and 3G, stock 4.3
I think I found a solution to the problem "Connection to server lost, touch to retry" on Wifi. In fact I used to encounter this problem on my Samsung Galaxy S2  device. The solution is as follows:


First make sure you have a Google account which you use to download applications from Google Play Store.
Open the YouTube application on your device.
At the top left hand corner of your screen, you would find the YouTube icon with 3 short lines to its left.
click on it (touch it) and there is a pop up menu which appears
If you have not yet signed into YouTube with the gmail account, the