I just changed the port on the other computer in the .cfg file and we both played a match, it didn't got me Auto-Disconnected yet... so I think this works now 

 It's most likely thanks to your help with the QoS rule 

 I just needed to use another port as well probably 

 Fingers crossed, hopefully I won't get problems now 

 Again, thank you for all your time, D-Link surely offers great support 
