After 2 update UTM, the slave UTM is dead !!

First time (1 month ago), the salve UTM (USG 220) was dead after update, and it was impossible to reinstall with CDROM.

  => Sophos maintenance send me a new UTM to resolve my problem because he doesn't know why !

Second time, after update to v9.414, the same problem : first UTM update ok, but the second is dead after update !

=> i want to reinstall by CDROM, but utm dont want (say "not the appliance material..."), but the UTM was new (1 month!!).

I have an idea : USG220 default was 2Go RAM and i upgrade to 4Go...

=> i reinstalled 2Go, and miraculous, CDROM install pass !!! YES

And reconnect in HA mode => synchro

ALL IS OK.

=> Is THE PROBLEM of update Salve UTM is the RAM capacity test ? maybe...

I suggere to Sophos Maintenance to study in depth this piste...