Trying to call some friends in Sing,same thing happens every night around 7 recently

The bottleneck of international internet traffic gets especially tight from 7pm on, nightly. I use Skype and typically get dropped calls, and a lot of "cutting out" of the signal or delayed signals any time in the evenings. It's usually so bad, that calls are often impractical during evenings.

Try the call at 6 a.m., and you'll see a huge difference (if you don't mind waking up your Singapore friends at 5 a.m. their time!)