Ive been wondering the same.
I have 1 computer with a 6 port USB and 4 USB Audio cards, and im running 4 feeds.
Most of the time all 4 run fine but once and a while one of them will not allow people to connect OR it will disconnect you from listening every 2-5 minutes. Logic tells me that since my other feeds are fine it has to be on the server side. But who knows. Everytime i try to get it fixed im told its on my end. Even though my other feeds dont have issues. go figure.. lol