TIH 2014 requires authentication for network now but not previously

Win 7 64. Have had a series of incremental backups across a network to a non password protected share drive that is shared with everyone and is also shared without password on homegroup.
Past backups have worked without a password, but now TI is asking for authentication.

Computers are connected via a switch.

Found a lot of older posts (2010 2011), tried using the homegroup path....but cannot eliminate the popup for authentication and if an attempt is made to change the settings on the backup the popup comes up again....Since there is no network password, do not know what to enter for a password and cannot leave it blank.

Any suggestions would be welcome.

Did start a new backup across the path by browsing and set a user name and password in the authentication box and the backup works. But how can I get the old backup to not ask for credentials as it was previously?

Any suggestion would be welcome.