Thanks for contacting support, I’d be happy to assist here. I have a few suggestions as to help narrow down this where this issue lies:
Can you please try rebooting your Nucleus, NAS and all Networking gear as the first troubleshooting step?
Has the username/password for that NAS by any chance changed? If you try to add the NAS path again Roon Settings -> Storage -> Add Folder -> Add Network Share, does it show up properly?
I noticed that you’re mounting your NAS via Hostname, does the same behavior occur if you mount the NAS via IP address? Mounting via IP address is generally a more stable way of connecting to a NAS, if you mount via IP address I would also recommend setting the NAS as a Reserved IP Address.
Are you still able to access other online content from the Nucleus? Is TIDAL still working as expected?
Can you please let me know what NAS & Router model/manufacturer you are using in your setup?
Have you by any chance updated the firmware for your router or changed any firewall settings on the NAS?
Please let me know your reply to my questions and if my above suggestions help resolve the issue.
If you run into any other issues don’t hesitate at all to reach out. Thanks again for contacting support and I wish you an enjoyable listening experience