mozda ovo pomogne (ako je taj prob. u pitanju):
When I try to enter the network mode I receive an error message (UDP port error)
If you receive an error message that you are unable to connect to the server, it means that you have one or more ports blocked on your internet connection, either by your Internet Service Provider, or if you are using a router, by your modem with router function or firewall software.
If the Router you are using is compatible with UPnP, please make sure that the UPnP function is enabled. Please disable any firewall/antivirus program on your pc. Also disable the Router’s Firewall function and make sure the following ports aren't blocked by your ISP (Internet Service Provider) and are open on your router (refer to the Router Manual in order to this):
TCP Ports: 80, 443, 8800-8899, 14020
UDP Ports: from 5730 to 5739
inace ovo sam iskopao na konamijevom sajtu,... moguce da te samo zeza firewall/antivirus program ako si instalirao neki novi u skorije vreme...