This too
I've had the same problem intermittently with the streaming services. Signing out and in again on the streaming services has solved it.
I love Roon, but I HATE that you have to be internet-connected to play YOUR OWN STORED MUSIC. They put that in recently, and, naturally, I went through a service outage just afterwards.
Yes, that's one reason why I keep a few CD players around. Long time Roon user, a couple of years ago, we had a week of no internet, and really loved the feature of being able to play my library. My solution to stability, is simply dedicate a power efficient linux server for the core, and go wired everywhere you can. I use an i3-10100 mini-itx. More powerful than most of those trying to use i7 NUC builds, and even more powerful than those dedicated Nucleus devices, last time I checked.