Monster Hunter Portable 3rd (HD Ver. or not)

[CryZee]

Hey guys,
my english isnt good but i try to post something.
I'm playing on my PC Monster Hunter Portable 3rd HD ver. In my settings I disabled "fastmemoryacces" and I have all Network settings enabled and have coldbird.net as IP-adress. I turned off windows firewall and forwarded some ports, I think. My ping to the UK is 70ms. If I join a random players quest everything works fine. We depart on quest without the alternative speed option and we are after 10 seconds in game and everything works. But if I am the quest leader and the same person joins my quest we broke off after 1 minute of loading. I tried it with a friend....same problem. We also used 25% alternative speed and it didnt work.
I really need your help. The random player has a important setting that we dont have and I want to know which!