Dedi Server Problems

[lipe123]

Short version, When I'm on LAN with the server I can play just fine. When on an internet connection (even a really fast one) I cannot catch up when connecting to the server, the catching up bar literally goes backwards and never completes.

The server is running Debian 8
Core i7 2600K cpu and 16Gb ram. Server resources are not under strain at all from the game and when I'm home I can play flawless on it.
My internet has an upload speed of 30MB/sec and when I play the game on LAN or from Internet connections outside my home the game only uses 16-32KB/s while playing so I don't see any speed problems.
Second my latency in ticks in the game is around 8 ticks and still cannot catch up or play without jumps starting to go up and buffers going up.

Server is not lacking resources, internet connection is not lacking resources this leads us to clients...

So my home pc is a i5-7600K with lots of ram and shiz and it plays the game flawless.

My friend has a i7 4770 and i have a i7 3770k with ssd's 16gb ram etc and these machines cannot catch up with the server. However if we save the MP map locally and run it in single player then it plays fine on these same computers.
When I set the game.speed to 50% or 70% then we can catch up and play fine.
to the clients?
What is the problem here? Is the game not using the available bandwidth properly to send the info to the clients?
Are these monster core i7 cpu's too slow to run the game? (come on get the multi thread stuff sorted out already PLEASE)

I'll attach the Map here for testing purposes.