Upgrade from 10.2.0-1789.0 to 11.5.1

It's odd they would recommend something without providing you a reason. The only thing I can think of us that 11.4.1 has been around longer then 11.5.1 - thus they wanted the most stable code for you, especially on a lower end F5 LTM.

However, I would insist with the your partner to determine why.

I hope this helps, -=Bhattman=-

We think like you, we are going to insist with our partner, thanks :)

My other recommendation is if you are not satisfied with our partners response is to contact F5 support or your Account rep and have their SE take a look at your configuration and do a "BUG Scrub" to make sure there is no compability issues with your configuration.

We do something similar at my work and it's helped us catch potential "Gotcha" in code upgrades.

I hope this helps,

-=Bhattman=-