I couldn't say with 100% confidence that my networking is configured entirely professionally, but only because I'm not super savvy on networking. Everything does seem to be working fine currently and maybe I'm speaking too soon but I think my issue has resolved. I'm about to hit 3 days uptime on the server without any issues, it's been getting used quite frequently this whole time, and typically by now, or by 24-48 hours the server would have crashed and I would have needed to hard reboot.
I think what happened is this: Initially I missed a C state setting in Bios (C1E) which needed to be disabled. The gigabyte bios on my board unfortunately doesn't have any global c-state toggle and I happened to miss the C1E setting. I toggled it off but then thought it didn't resolve anything because at that same time is when I had flashed bios and the LAN drivers seemed to fail. So then I updated BIOS not realizing it essentially flashed bios again and booted it with all C states on, of course, with no success, making me think the C1E disable didn't change anything. Once I realized though that BIOS was back at default, and I never actually got a boot with C1E disabled, I reconfigured BIOS once again, this time with ALL C states off (as far as I can tell), and now the server is up for 3 days with no issues.
I'll give it a week before I call it good but I feel confident right now that this was the issue and everything is now configured as it should be.