https://help.tallysolutions.com/docs/te9rel60/Data_Management/Connectivity_and_Compatibility_with_TS9.htm

Connectivity and compatibility in Tally.Server 9 Environment

Tally.Server 9 needs to be connected to the Internet for smooth operations which include user authentication and license management.

Connectivity

If Tally.Server 9 has not been connected to the Internet for 30 days, in the List of Tally.Servers in Tally.ERP 9, information on the number of days till surrender will be displayed (Will be Surrendered after x day(s)):

Users need to ensure that Tally.Server 9 is connected to the Internet to avoid License Surrender.

Incompatible version of Tally.Server 9 used with Tally.ERP 9

Tally.ERP 9 Series A Release 4.51 or a higher release will crash with the following error message if Tally.Server 9 Release 4.5 is used for data sharing:

Users need to upgrade to a higher release of Tally.Server 9 to continue working on Tally.Server 9 data.

Incompatible version of License Server

The following message will be displayed in Tally.ERP 9 Series A Release 4.5 if Tally.Server 9 Release 4.51 or a  higher release is used alongside License Server 7.8:

Users need to upgrade to License Server 7.9 for smooth operations.

Incompatible version of Tally.Server 9 used with License Server 7.9

The following error message will be displayed in Tally.ERP 9 if Tally.Server 9 Release 4.5 is used alongside License Server 7.9:

Users need to upgrade to a higher release of Tally.Server 9 for smooth operations.