2500baseT/Full not in "Advertised link modes"

[proxtib]

Hello.

My proxmox server has a 10Gb network card and he is behind a 2.5Gb switch.
But with iperf3 test, I observe that I only have a speed of 1Mb/s.

When I execute ethtool on one of my interface , I have the following result:

ethtool enp35s0f1
Settings for enp35s0f1:
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: umbg
Wake-on: g
Current message level: 0x00000007 (7)
drv probe link
Link detected: yes

It misses "2500baseT/Full 5000baseT/Full" in the "Advertised link modes" part.

Supported link modes:   100baseT/Full 1000baseT/Full  2500baseT/Full 5000baseT/Full 10000baseT/Full
Advertised link modes:  100baseT/Full  1000baseT/Full 10000baseT/Full

I found the following command to force the 2.5Gb. OK, It's work !
ethtool -s %i speed 2500 duplex full autoneg on

But is the "right way"?
Is there any way to get :

Advertised link modes:
    100baseT/Full
    1000baseT/Full
    10000baseT/Full
    2500baseT/Full
    5000baseT/Full

Do you have any idea what is causing this problem?
____

RedHat similar bug with networkmanager : https://bugzilla.redhat.com/show_bug.cgi?id=1897004
Similar issue on Archlinux: https://bbs.archlinux.org/viewtopic.php?id=262075