What were you trying to do that didn't work?

Customer was trying to configure ethtool coalesce parameters (for example rx-frames) persistently using NetworkManager via the nmcli command, so that the settings would be automatically applied when the connection is brought up.

However, after activating the connection, the configured ethtool.coalesce parameters were not applied to the network device, even though the same values work immediately when set manually with ethtool -C.

RHEL Version: 8.10

NetworkManager-1.40.16-15.el8.x86_64

Driver:  mlx5_core

Steps to reproduce

1. Modify an active Ethernet connection with nmcli to include an ethtool coalesce parameter.  e.g.  nmcli connection modify ens1f0 ethtool.coalesce-rx-frames 8
2. Bring the connection up.   e.g. nmcli connection up ens1f0
3. Check the current coalesce settings with ethtool -c

Expected results

It should be applied to the network device when the connection is activated.

Actual results

The configured value is not applied. However apply the same value manually with ethtool -C, and observe it takes effect immediately.