Exchange 2013 Active Sync TTL Adjustment

Hello all. Likely an easy question but I would like a second opinion from the experts here before I introduce a change. In my Exchange 2013 servers, I repeatedly see a warning that it is not getting the expected amount of heartbeats from Active Sync clients. After researching this a bit, it's looking like the TTL's are not set high enough somewhere in the chain for Active Sync connections.

Let me give a brief overview of how Active Sync traffic hits my Exchange CAS servers:

WAN/Firewall -> External (DMZ) LTM -> Internal LTM -> 2 Exchange CAS boxes

All F5's are using the Exchange 2013 iApp. I have checked the firewall and the TTL's are acceptable there (15 min), however, I don't believe the TTL is high enough on the F5's. I went into Local Traffic ›› Profiles : Protocol : TCP ›› Exchange_2013_lan-optimized_tcp_profile and found that the "idle timeout" is 300 seconds (which is a bit low). I BELIEVE setting this to 600 seconds (10 minutes) on each F5 in the chain here would resolve the issue or at least mitigate it and then I can go up or down from there. Has anyone on here ever seen something similar? Is there an alternative that is more strongly recommended for this scenario?

Thanks all!