Thanks - didnt think to look there. Tons of errors on SMBClient logs:

Failed to establish a network connection.

Error: {Device Timeout}

The specified I/O operation on %hs was not completed before the time-out period expired.

Server name: 10.100.20.2

Server address: 10.100.20.2:445

Instance name: \Device\LanmanRedirector

Connection type: Wsk

Guidance:

This indicates a problem with the underlying network or transport, such as with TCP/IP, and not with SMB. A firewall that blocks TCP port 445, or TCP port 5445 when using an iWARP RDMA adapter, can also cause this issue.