What is the uplink speed of a VPS?

Short Answer

100 Mbps

Detailed Answer

Each VPS shares a 100 Mbps uplink with other VPS's running on the same host machine. You may see your VPS detect a NIC with 1 Gbps max speed, but this is merely the host providing emulation of a chipset that registers at 1 Gbps (such as the Intel PRO/1000 e1000 family). The actual uplink is still 100 Mbps.