How to set or get the link speed of an network adapter

[seanwin]

How to set or get the link speed of an network adapter？

If i use CurrentLinkspeed  to get the link speed of a network adapter, it will show an err as follow.

 

If i use PreferredLinkSpeed   to set the link speed of a network adapter, it will pass, But the link speed is not be changed.

Does anyone can help me about this, Thanks a lot.