Secure Communication Protocol

If you plan to upgrade from a lower AsyncOS version (for example, 13.6.x) with TLSv1.0 enabled to AsyncOS 13.8.x and later, then TLSv1.0 is disabled, TLSv1.1 and TLSv1.2 are enabled by default. You need to enable the TLSv1.0 method on your appliance after the upgrade.

From AsyncOS 15.5 and later, it is recommended to use TLSv1.1, TLSv1.2, and TLSv1.3 (for Appliance Management Web User Interface) methods instead of TLSv1.0. TLSv1.3 is disabled by default, and you must enable it.