Really wish I could help you duplicate this. I sit in the chat for hours at a time, like up to 8 hours sometimes, and no disconnects. Also the chat tells you when someone has quit or entered a room and I don't see people mentioning it, nor do i see people consistently being dropped.
Unfortunately one of the worst words I ever had to hear being a tech is intermittent which usually meant I was never going to see it.
I don't think there is any sort of cover up from people to not report this, most users love to complain even when something is free, so I would think there would be more posts on the issue.
If you could actually get any of these other people to keep some sort of log or screenshot of when it happens maybe we could narrow it down, but as it is, we just have several threads from you with the same problem.
As it is I really don't know what to offer you on this, my internet tends to slow down in the evening with heavy use from the populace sometimes tt he point where chat lags a bit, but even then I don't get disconected.
Maybe you can find some sort of bandwidth monitoring program and see what is actually going on during those times.
Something like this maybe.
Bandwidth Monitor - Monitor Bandwidth, Network Bandwidth Monitor, Bandwidth Monitor Software