That’s the ROCK build but Roon has released numerous core releases since Rock b254 shipped in November. I believe Roon uses CIFS for SMB - in the case of a ROCK, I’m not sure if CIFS updates only with ROCK updates or also potentially with Roon updates.
I’m not claiming, though, to have a theory about root cause. Something broke for @Mikael_Ollars. Here’s an example of another case where connectivity to a NAS (Synology in this case) also recently broke:
In both cases, the broken case involves anonymous logon. In the case of the Synology user, we recommended he try putting access control on his music folder and updating his Roon settings. We haven’t heard back.
I could be wrong but there are worse strategies than triangulation when debugging…