Upload Speeds Drop At The Same Exact Time Every Night For Months

I have been dealing with an issue now for about 4 months that consists of my internet speeds dropping (mostly upstream) at the same time every night. At about 9:15 pm Central Time my upstream drops to below 1 Mbps from anywhere between 45 minutes to multiple hours. I do streaming on Twitch and spend a lot time gaming so this is my peak hour for these activities and they are greatly affected by this upstream issue.  I have had around 7 techs out who have changed everything they can and have ruled out anything wrong at my tap or at my residence. I was eventually given the number to a shift supervisor that I could call when the issue was occurring where I was to leave a message with my name an number and they would look into it and get back the next day. I have stopped receiving callbacks and am at a loss as to what to do next. I have had confirmed packet loss during these periods that I see through the trace routes I run and from the supervisors I have talked to. I was also told by this supervisor and technicians that have been out that congestion should not be an issue as I am the only active subscriber on my tap so that has been all but ruled out.

If anyone is willing to give me some direction or work with me I would greatly appreciate it as coming to this forums is my last ditch effort in trying to figure this issue out. Thank you so much for your time.