Server lag (momentary packet loss) ???

Hey all!

I have the following problem with my server:

I have 1 server with the gamemode “jailbreak” but when people starting to shoot each other the server has a strange lag.

Its not fps lag or what ever. For example if there are like 5 people in the server and 2 people shooting each other then the other 3 people are like moving on there on when they standing still.

A friend of my said: when somebody fires a gun, there is a random chance that this will cause the server to stutter and all players will experience momentary packet loss

My download speed is 43 mbps
My upload speed is 3.63 mbps

I have a xeon procesor dual socket 2011 and 64 GB intern memory ddr3

It looks like this and the picture

I am willing to pay you 50 euro if you can fix this