That error indicates that the backup timed out after waiting to connect to the backup servers. The likely cause is an unusually high volume of users hitting one particular server at once. Typically this error is temporary in nature, will auto-resolve itself and does not arise often.
Is it possible for the both of you to initiate a manual backup, outside of the usually scheduled time range, and advise of its result?
You can accomplish this by right-clicking on the NOBU icon located in the taskbar tray and selecting 'Backup Now'.