I guess it's a vmxnet3 otherwise the single Veeam server would not be able to send data at 200MBs as Kasper is saying, unless this is the apparent speed read in Veeam, since that also counts all the data savings coming from compression, dedupe and empty blocks.
How is configured the Veeam virtual machine? cpu, ram...
EMEA Cloud Architect @ Veeam Software
Veeam VMCE #1