What firmware to use for TL4000 with LTO4 drive?

I've got a TL4000 tape library with the following firmware info:

I have two LTO4 half height SAS drives.  The problem I'm having is that we run frequent network scanners to look for vulnerabilities and that seems to be confusing it requiring me to reboot the tape library.  There have been several newer firmware versions released after that version but mostly they seem to be for newer tape drives. 

What is the most recent firmware I should be at?    If I do manage to upgrade the firmware to a version that can't deal with my tape drives, will it let me downgrade back to that old library firmware version?