Thanks. The IP address is fine. I can access the Network Storage Manager, but the advice on the reset is clearly a last resort:
"Restoring the device to the Factory Default will destroy all data on the device, including all configuration setup, all shares, and all user data and media files. After the restore is complete, the device configuration will be identical to its state at purchase."
I need a solution that won't remove all my data. Is there another way to solve the problem?