We had a very similar problem at our office where 1 pc could connect but all others would not. Per ICON it is a PC problem and here are the steps to fix it...

Computer Management -> Device Manager -> Network adapters -> then select properties of the installed adapter -> advanced tab

"UDP Checksum Offload (IPV4)" Set the value = "Disabled" and click "OK".

If you can't change it on the NIC, you will need to google the Windows registry change to fix it or use a serial connection.