Streaming to Twitch - Intermittent Connectivity, restarts stream every 5-25 minutes.

A little background: I'm using the 1200 down 35 up package for internet speed, running a 3090TI and tons of RAM etc while utilizing a dual PC stream for Twitch. My speed tests show that speed is up to par, both in terms of download and upload. However, when I attempt to live-stream to Twitch, I lose connection every 5-25 minutes. I continuously get the update in my notification tab informing me that connection has been lost and it is attempting to reconnect. People in my chat ask me if there is a problem with my OBS frequently, advising me that the stream has dropped, and it is frankly infuriating at this point. Tonight, for example, I attempted to stream for just shy of 3 hours. At the conclusion, when looking at my video producer, I count 9 different "streams" all with the same title--indicating that I lost connectivity for long enough for it to be considered a new upload segment, 9 times, within less than 3 hours.

I cannot adequately express my frustration, having shelled out for premium equipment all the way around, only to have inadequate and inconsistent service. I have been at this location for about 6 months now and I have been through numerous hoops: I have sent innumerable refresh signals, changed out ethernet cables, changed ethernet switches, played with all kinds of settings, all to no avail. I typically run on a bitrate of 6000 and there are rare occasions (I'll say 1 in 3 streams) where I can go for 8+ hours without any difficulty, no disconnects. Then there are nights like these where I'll see my bitrate crash (even with dynamic bitrate allowed) down to less than 2500 repeatedly, the stream disconnecting and reconnecting intermittently, people in the chat saying they can't see anything or that the stream is "frozen" etc. Even if I drop the bitrate to 2500 by default (should be totally unnecessary if I'm getting anywhere near 35 upload) it still happens with the same frequency.

At this point I'm just wondering, can it be helped? Should I have a tech come out to my house to check wiring from my place to the street? I can hardly imagine the issue is something within my personal means to fix at this point. Having moved here this year, I know that nothing has changed on my end other than cables--which I've already ruled out as potentially being the problem.