Dear Vincent,
So I assume you have 3m samples per second, one sample is 2 bytes, and you have I/Q so you would need a 3*2*2 => 12MB/s (Mega bytes per seconds).
This might fit or not. Only tests will tell. It will also be system dependent, the complete scheme relies on the host CPU parsing packets and on Windows, because the scheduling, you will not be able to predict a realistic time (not real time).
We did not characterize the Ethernet link because once again it was not designed to stream data back and forth but simply to offload small snapshots. Just try but this sounds too much data for the link.
Best Regards,
Arnaud