When you use a 10/1G SFP+ module you will see 1G is an available setting:
[22.09-DEVELOPMENT][admin@6100.stevew.lan]/root: ifconfig -vm ix1
ix1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
description: IX1
options=8138b8<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,WOL_UCAST,WOL_MCAST,WOL_MAGIC,VLAN_HWFILTER>
capabilities=f53fbb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,WOL_UCAST,WOL_MCAST,WOL_MAGIC,VLAN_HWFILTER,VLAN_HWTSO,NETMAP,RXCSUM_IPV6,TXCSUM_IPV6>
ether 00:08:a2:12:17:7f
inet6 fe80::208:a2ff:fe12:177f%ix1 prefixlen 64 scopeid 0x6
inet 192.168.79.2 netmask 0xffffff00 broadcast 192.168.79.255
media: Ethernet autoselect
status: no carrier
supported media:
media autoselect
media 1000baseSX
media 10Gbase-SR
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
plugged: SFP/SFP+/SFP28 10G Base-SR (LC)
vendor: FINISAR CORP. PN: FTLX8571D3BCV-CK SN: ANL1C1V DATE: 2012-11-21
module temperature: 40.65 C Voltage: 3.33 Volts
RX: 0.01 mW (-17.28 dBm) TX: 0.63 mW (-1.99 dBm)
And the speed/duplex field in the gui will reflect that.
Steve