after adding an interface card to F5 vm's (version 11) after rebooting some of the configuration was deleted, is there a reason for it?
The simplest reason I can imagine is that the configuration was not saved and after reboot an older version on the *.conf files was loaded.
If you do configurations via Web GUI (aka Configuration Utility), changes are automatically saved.
But if you changes in the tmsh CLI, changes are *NOT* saved. You must issue a "save sys config" for that to happen.
to start with version 11 is quite old, you might just have ran in some bug. see if you can get this upgraded.
just from version 15 adding interfaces seems to work without issues