Married, we both work from home, and we’re in an apartment.
First, all of my weird stuff is not between her work and living room pcs and the internet. Cable modem connects to normal consumer router (openwrt) with four lan ports. Two of those are directly connected to her machines (requiring a 150-ish foot cable for one), and two connect to my stuff. All of my stuff can be down and she still has internet.
Second, no rack mount servers with loud fans, mid tower cases only. Through command line tools I’ve found some of these are in fact capable of a lot of fan noise, but this never happens in normal operation so she’s fine with it.
Separately I’d say, have a plan for what she will need if something happens to you. Precious memories, backups, your utility and service accounts, etc. should remain accessible to her if you’re gone and everything is powered off - but not accessible to a burglar. Ideally label and structure things so a future internet installer can ignore your stuff and set her up with normal consumer internet after your business internet account is shut off.
Also keep in mind if you both switch over so every movie and show you watch only ever comes from Plex (which we both like), in an extended power outage situation all of your media will be inaccessible. It might be good to save a few emergency-entertainment shows to storage you can browse from your phone, usb or iXpand drive you can plug directly into your phone for example.