Cannot set RX/TX channels on ConnectX4 MT27700


I recently got a ConnectX4, and I found that I cannot set RX / TX channels using ethtool as I was able to do with the ConnectX3 Pro. If I check, I see:

# ethtool -l ens5f0

Channel parameters for ens5f0:

Pre-set maximums:

RX: 0

TX: 0

Other: 512

Combined: 36

# ethtool -L ens5f0 tx 3

Cannot set device channel parameters: Invalid argument

which seems a bit weird. I had a look at the documentation, and found nothing in this respect. Is this something expected? I am using, and:

CA ‘mlx5_0’

CA type: MT4115

Number of ports: 1

Firmware version: 12.20.1030

Thanks a lot for any help!