If YouTube videos are playing intermittently, then Please try out the following steps for resolution -
a. The minimum internet speed required for playing YouTube in normal quality is 2Mbps and to play HD quality videos minimum speed required is 4Mbps.
b. Try to restart Wi-Fi router. The network may be clogged if many devices are connected to the same network.
c. Try to check if the Wi-Fi router has been configured according to the settings mentioned in the link below- http://teewe.in/wifisettings.