Different ping times on Omniswitches

[20deoctubre]

I have uploaded my network diagram. I have a novice doubt with two Omniswitches, this isn't about configuration.

Why are my Omniswitches responding differently my pings ? One of them are cutting service in randomly lapses (for example, every 5 or 6 minutes the internet goes down, so it does it too my ping to the closest switch 101.40.4.3 (the internet doesn't goes down on the internal LAN behind the 101.40.4.2), but the ping to 101.40.4.2 is not falling down. Another thing, the closest Omniswitch (101.40.4.3) is responding slower the ping than the other switch (101.40.4.2) I have shown this too in my attachements. Why is this happening ? My logic tell me that 101.40.4.3 (the closest switch) should respond faster than 101.40.4.2 because I'm directly connected to 101.40.4.3, but 101.40.4.2 is responding faster than 101.40.4.2.

Both switches are running on default vlan 1.
On 101.40.4.3 are connected just my PC and 101.40.4.2 (LAB purposes).

Thanks un advance
Regards