From the information presented, this seems like a plausible explanation;
1. Your network connection was erroring
2. So nothing, including NTP and VOIP, worked
3. You called to complain
4. They fixed the connection
Does that fit? You didn't say what the result of calling "ISP telephone support" was.
Whch is to say, I don't immediately see a reason to conclude anyone was being attacked.
It would help us to understand it if "time initialized fail" could be rewritten in English though
By which I mean words like "time initialization failure", or "time initialized, then failed", or something of that ilk.