Ethernet Interface speed of 1000 is not an option in the Advanced tab of the Ethernet settings.

The 1000BASE-T standard specification (IEEE 802.3ab) states that autonegotiation is a requirement, according to Section 28D.5 Extensions required for Clause40 (1000BASE-T).

As autonegotiation is a specification requirement, the option to select 1000 as the speed has been removed.