Taking a step back, if I understand correctly, you have your existing Sooloos system, based on the MC200 as core and store and a new Roon system for which the store is USB drive attached to your router.

What runs the core for Roon and how is that connected to your network?

I'm also curious about how the MC200 is/was connected to your 808. As Carl says, ideally you'd have that wired to the same switch (or router, although some say this is less desirable) as your 808. The hypothesis being that an MC200 (or MD600 for that matter) is ultimately a computer, which is a too noisy a device to plug directly into your 808.

Antipodes CX + Roon, 818v3, DSP 7200SEs, 218, DSP3200s