Today I installed a HPE Eth 10gb 2p 562T Adptr NIC (Intel X550T) on my Proxmox Server

However, X550T did not nego 2.5GbE with Mikrotik RB5009

Make it Work

To make it work, open Proxmox Terminal and apt install ethtool

Then type ethtool eth0 to view Current Speed and Supported Mode

root@hitoha:~# ethtool enp5s0f0
Settings for enp5s0f0:
        Supported ports: [ TP ]
        Supported link modes:   100baseT/Full
                                1000baseT/Full
                                10000baseT/Full
                                2500baseT/Full
                                5000baseT/Full
        Supported pause frame use: Symmetric
        Supports auto-negotiation: Yes
        Supported FEC modes: Not reported
        Advertised link modes:  100baseT/Full
                                1000baseT/Full
                                10000baseT/Full
        Advertised pause frame use: Symmetric
        Advertised auto-negotiation: Yes
        Advertised FEC modes: Not reported
        Speed: 1000Mb/s
        Duplex: Full
        Auto-negotiation: on
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        MDI-X: Unknown
        Supports Wake-on: d
        Wake-on: d
        Current message level: 0x00000007 (7)
                               drv probe link
        Link detected: yes

As you can see, Advertised link mode just 100Mbps, 1Gbps and 10Gbps, we can change this by add more mode

Mode	Hex
100baseT/Full	0x008
1000baseT/Full	0x020
10000baseT/Full	0x1000
2500baseT/Full	0x800000000000
5000baseT/Full	0x1000000000000

Now sum up all Hex value like this in terminal:

printf "0x%X\n" $((0x008 + 0x020 + 0x1000 + 0x800000000000 + 0x1000000000000))

Total is 0x1800000001028 then we can run command:

ethtool -s eth0 advertise 0x1800000001028

To confirm working, see:

root@hitoha:~# ethtool enp5s0f0
Settings for enp5s0f0:
        Supported ports: [ TP ]
        Supported link modes:   100baseT/Full
                                1000baseT/Full
                                10000baseT/Full
                                2500baseT/Full
                                5000baseT/Full
        Supported pause frame use: Symmetric
        Supports auto-negotiation: Yes
        Supported FEC modes: Not reported
        Advertised link modes:  100baseT/Full
                                1000baseT/Full
                                10000baseT/Full
                                2500baseT/Full
                                5000baseT/Full
        Advertised pause frame use: Symmetric
        Advertised auto-negotiation: Yes
        Advertised FEC modes: Not reported
        Speed: 2500Mb/s
        Duplex: Full
        Auto-negotiation: on
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        MDI-X: Unknown
        Supports Wake-on: d
        Wake-on: d
        Current message level: 0x00000007 (7)
                               drv probe link
        Link detected: yes

You will see Speed is 2500Mb/s and Duplex Full and Mikrotik RB5009: