>>>>
>>>>Also, keep in mind that when you're performing a backup on the server, the server can only access itself and not the user's computer.
>>>
>>>Dear Teacher Naomi
>>>
>>>I am unable to understand what you said in above sentence.
>>>Please write again in some easy wording.
>>
>>The disks in your command ("c:\" etc) are disks on the machine where SQL server service is running, not on the machine where you sit. So the path of your backup needs to be on the server, and needs to exist on the server - or, if it's a network path, it has to be visible from the server. Because that is where the commands you send will be execute
>
>Just found this way to make a network drive visible to SSMS (other than using an iSCSI drive): https://www.mssqltips.com/sqlservertip/3499/make-network-path-visible-for-sql-server-backup-and-restore-in-ssms/

I don't understand the point here... is SQL unable to see an UNC or is it yet another limitation (pardon the euphemism) of SSMS?

Of course, the rights to see are part of it, but I guess the same issue would apply to a mapped drive, so that part isn't different. The accumulated experience with mapped drives under various doses and windowses has taught me that these may be slightly unpredictable. May vanish without notice.