ax0: xgbe_phy_sfp_signals: port_sfp_inputs: 0x0ax0: SFP detected:ax0: vendor: CISCO-AVAGO ax0: part number: ABCU-5710RZ-CS4 ax0: revision level: B2 ax0: serial number: AGM165220FH miibus0: <MII bus> on ax0e1000phy0: <Marvell 88E1111 Gigabit PHY> PHY 0 on miibus0e1000phy0: none, 1000baseSX, 1000baseSX-FDX, 1000baseT, 1000baseT-master, 1000baseT-FDX, 1000baseT-FDX-master, autoax0: Link is UP - 1Gbps/Full - flow control off
SFP copper is notoriously unreliable.