LTM 11.5.1 cluster is not stable

Hard to know without more information. What HA features do you have configured and how?

after upgrading the two units from 11.5.1-HF1 to 11.5.1-HF2, I face the issue. features are Network failover multicast unicast mirroring between clusters ASM fail-safe enabled failover method is HA irder

Ok, thanks. Do you see any useful errors in the logs?

Is there a reason you are using multicast and unicast for network failover?

Are the related switch ports stable?

Not sure what you mean by HA order?

Hi, I didn't see any logs as per F5 documentation I did both multicast and unicast switch is ok HA order it is under Device Management --> Traffic Group --> Properties --> Advanced Option

by the way both units were working properly before installing 11.5.1 hotfix 2

Perhaps the quickest thing to do is rollback? Just before you do, can you try turning off the multicast network failover, I'm sure you shouldn't use it together with unicast.