Really bad desync only in my network

[bartbergmans 0]

Hi guys,

Since a few days I can't play DayZ the way it should be. Sometimes I have a desync of 100k or I have 0 desync but I still get Receiving on every item and I don't see my friends walking. 
When I play with my girlfriend who sits next to me and is connected to the same network also has connection problems but not as bad as I do. 

My friend who lives a few kilometers away from me doesn't have any of these problems.
What can I do to fix the connection problems at my PC/network?