(my internet) Possible serious network issues

When you lose connection, immediately right-click on the network and sharing center icon by your system clock. Click your internet connection and look for incoming and outgoing packets. Do you see any insane / impossible jumps, like 1m+ incoming per second?

Message me on Steam, we can do 2 or 3 things (before you restart the modem) to ensure that the symptoms are not repeated if this is, in fact, some kind of attack

 

If you think you are ddosed you can use a network command netstat -a to show your open TCP & UDP Ports and what remote addresses your computer is connected to. So go to "run" then type cmd, then type netstat-a.
Check ip on whois or Arin... hers some guide about ddos prevention.:
copy paste to your browser
http://lol.gamepedia.com/DDoS_Prevention_Guide

Second if somone want the ddos or hack you for real should have your IP adress, so if you did not give somone your IP it would be very hard to find you and ddos you. Unless you maybe use Teamspeak.
Try test your nettwork with wireshark
https://www.wireshark.org from Wiki : Wireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocoldevelopment, and education.

But maybe u have some problem with your modem anyway people from your provider saying that modem is all right. does need all people work there is professionals.
I ll never forget some years ago my family member had problem with hes hewlet packard PC crashing so often , i ll called support here in Norway on www.hp.no and guy told me on phone that i need open both side of the case to cool pc down -.- and that will fix the problem.zomg