SMB and GUI suddenly stopped working - TNS Cobia

Hello, everyone.

A kind of poltergeist situation - my TN Scale Cobia was working without a hitch until this morning when I received an email from my backup software saying that my backup to NAS failed. I checked the mapped drive in Windows 11 and saw that the SMB share is not connected for whatever reason.

I went to the GUI and got a connection refused error when I tried opening the GUI by FQDN and IP address.

Disconnected/deleted the mapped drive and tried to reconnect with error 67 from Windows. Can’t connect.

Stopped all VMs on the hypervisor nodes and restarted the TrueNAS machine from console and then even rebooted the hypervisor nodes. They got reconnected to both NFS and iSCSI shares on TrueNAS and VMs started up properly.

Shutdown / powered up all infrastructure including switches suspecting that they may probably are casing issues. Same thing, can’t reconnect SMB shares and can’t access the GUI. I also can’t SSH into TrueNAS as well, connection refused on the interface.

I have one SMB share with ISO images and it was set up as an ISO storage repository on one of my XCP-NG hosts. When I just discovered the issues I noticed that this ISO share is disconnected on the hypervisor node. After rebooting the nodes the share was still disconnected but I was able to reconnect it manually. So SMB works between a Linux-based hypervisor and TNS.

What am I dealing with here, any ideas?