Intel i226-V Rev 4 only running at 1000 Mb/s

Hardware Hub Networking
1

As the title states, my PCI-e card is running at 1000 Mb/s instead of 2.5Gb.
Kernel 6.8.0-49-generic (Ubuntu 24.04)

sudo ethtool enp49s0
Settings for enp49s0:
	Supported ports: [ TP ]
	Supported link modes:   10baseT/Half 10baseT/Full
	                        100baseT/Half 100baseT/Full
	                        1000baseT/Full
	                        2500baseT/Full
	Supported pause frame use: Symmetric
	Supports auto-negotiation: Yes
	Supported FEC modes: Not reported
	Advertised link modes:  10baseT/Half 10baseT/Full
	                        100baseT/Half 100baseT/Full
	                        1000baseT/Full
	                        2500baseT/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: off (auto)
	Supports Wake-on: pumbg
	Wake-on: g
        Current message level: 0x00000007 (7)
                               drv probe link
	Link detected: yes
2

Have you tried manually setting it to 2.5G using ethtool? It does show as advertised & supported so maybe that works.

3

Yes, I’ve tried setting the rate with ethtool, when I do, the network adapter goes offline and I have to reboot. Then it’s back to 1000Mb/s.

4

What NIC, tried another cable (you probably need at least CAT6/6A) and/or direct connection to the other end?

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5

NIC is in the title. Cable is Cat 6.

6

Yeah these nics (Intel 225 and 226) have their fair share of issues. I had some as well where it ate its own firmware. Which device do you have exactly? Check the manufacturer for possible firmware upgrades.

But these are known to have issues with negotiation and stability especially at 2.5Gb.

7

What NIC is connected to the other end of the cable?

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8

NIC is connected directly to a 2.5Gb 8 port unmanaged switch.

9

UPDATE: Appears the cable was at fault, I’ve since replaced it with a brand new shielded Cat6a and everything is working as expected. Thanks folks :slight_smile:

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