Unfortunately, this didn't resolve the issue. But hey, at least now we're running fiber like a real datacenter.
After lots of troubleshooting and chancing upon a forum post, I discovered that there seems to be a bug in the BIOS for the X10SL7-F motherboard in my FreeNAS server. Changing a BIOS setting fixed the issue. Thank god for people who come back to their forum post and reply with an explanation of the solution.
I realized that used RAM is totally viable as long as you test it, so I returned the 32 GB of new RAM I had originally ordered, and bought 64 GB of used RAM from someone on reddit.com/r/homelab for the about same price.
Lots of room to grow