Hello,

Cause the connection will drop out now and then, it is suggested to confirm the stability of the modem/internet source first. 

In other word, please connect your computer to the modem directly and check whether you can access interent when the internet led does not glow.

Meanwhile, you can change another cable with better quality to connect them; and you can change another port on the modem/ internet source. 

May it help. 

Nice day.