internet service is down every night at around 9pm

This has been going on for a while. It started out with my old modem - it was Arris/Motorola SBG, used to have disconnects every night.  A Comcast tech suggested me to upgrade the cable modem, so I bought CM1100. It worked for only a couple weeks flawlessly, but now, the old problem resurfaces. 
I recently had an online chat with an agent bp-rsidat156. He agreed that during this hour neighboring homes are accessing the internet at the same time - so it's peak hour. He suggested me to use xfinity hotspots. If I have to, I would. The problem is where my desktop is located, I can not receive any xfinity signals. Besides, who wants to be connected to unprotected hotspots while paying hundreds of dollars every month.
After spending like 30minutes, he claimed that he did an 'advance reset' to a Comcast device - he didn't tell me whether it's a CMTS, or what. Anyway, the internet service was back online - but I knew it won't last - it went down after staying up for only 10 minutes. By then, the chat had already been closed (I was using my PC through hotspot service off of my cell phone).
So, I thought, why don't I try upgrading my home internet service - I did Performance Pro - 200Mbps just now. But the service was never online.
My family keeps screaming at me. I'm hopeless at this point. Am I the only unlucky one in this whole neighborhood? Do I have to pay different service tier like 1Gbps per month to make a difference? Does anybody else experience this same issue? What's the remedy? Do I have to hire a lawyer?
I'm really at loss here. Can Xfinity rep contact me? I really need a resolution here. I'm willing to pay more if you guarantee I can access the internet service reliably all the time.