Server Connection Issues

I am having some problems with my dc++ network I am running a Ynhub on a windows server 2008 standard machine and am having trouble with users getting file lists from each other. Everyone can connect to the hub nicely but when they try to get each others file list some people can get lists others can't. Is there anyone out there that could help me with my issue? I am thinking the network i am on has a lot to do with it but i have talked to the people managing it and they have checked that none of the ports that dc++ uses are blocked. But if that is true what could be hindering transfers? the building i am in has eight vlans and i have been assigned a static ip address and run a vent server a web server a ftp server and dc++ hub on the server. each port in the building is flow controlled 3mb down/ 1.5mb up obviously this hinders transfers between computers but is that speed so slow that the dc++ software can no communicate? The people managing the network i am in have said they would give me a port in the comms closet with a 3mb down / 3mb up but im not sure if that will put be above the vlans so that i would have a ip out side the vlans giving every computer in the building access to my server, but i don't know if that is possible. please ask me any questions you have if i have not explained my situation completely.