We have a single physical server running XenServer 6.2 which hosts an SBS 2008 VM and 2 CentOS 6 x64 VMs.
External users connect to the local network via VPN on the SBS VM. They can access everything, however one of the CentOS VMs streams files extremely slowly. For external users, the average transfer rate for this VM is 30KB/s compared to the other CentOS VM which averages at 1MB/s. Our Internet upload speed is 10Mbit. For internal users, the average transfer rate for both servers is 50MB/s. Our internal network speed is 1GBit.
So far I have tried placing all VMs on to the same physical NIC and rebooting the host but to no avail.
The NIC firmware has been updated to the latest version and we are using the drivers that came with XenServer. Our NICs are the Broadcom BCM5708C NetXtreme II GigE (LOM).
Both CentOS VMs use 8 cores, 4GB of RAM and have plenty of VHD space.
Any ideas what else could be causing this problem?