What causes BIG-IP LTM to go offline?

what are the possible causes for LTM to go offline?

Hi Mahmoud, it is hard to say that why ltm go offline without look at the log files. You can connect to ltm from ssh and check out the ltm file in the /var/log/ directory. it will give you clue that why ltm go offline.

there are many files and directories under /var/log which file shall i check

/var/log/ltm. looking around the time bigip went offline.

Hi Mahmoud, by that way I encountered a similar problem before when i try to do HA configuration between the units. if both units has communication problem with the each other then both unit goes offline mode.

both units were working properly, this issue happened after installing hotfix 2 for 11.5.1