CRS312-4C+8XG port failure

Hardware MikroTik hardware general
1

Suddenly one of my ports of the switch is acting weird. It can no longer make a connection. The connection fails to negotiate. If I plug in in any other port it works just fine. In linux I get the following

[ 451.466007] i40e 0000:01:00.0 eno1np0: NIC Link is Up, 5 Gbps Full Duplex, Flow Control: None, EEE: Enabled
[ 451.856198] i40e 0000:01:00.0 eno1np0: NIC Link is Down
[ 480.331807] i40e 0000:01:00.0 eno1np0: NIC Link is Up, 5 Gbps Full Duplex, Flow Control: None, EEE: Enabled
[ 480.645343] i40e 0000:01:00.0 eno1np0: NIC Link is Down
[ 492.999672] i40e 0000:01:00.0 eno1np0: NIC Link is Up, 10 Gbps Full Duplex, Flow Control: None, EEE: Enabled
[ 493.376491] i40e 0000:01:00.0 eno1np0: NIC Link is Down
[ 493.934178] i40e 0000:01:00.0 eno1np0: NIC Link is Up, 10 Gbps Full Duplex, Flow Control: None, EEE: Enabled
[ 503.397297] i40e 0000:01:00.0 eno1np0: NIC Link is Down
[ 545.124223] i40e 0000:01:00.0 eno1np0: NIC Link is Up, 5 Gbps Full Duplex, Flow Control: None, EEE: Enabled

I haven’t touched the config. I did update to the latest release software though a few days ago. It only happens on one of the ports. I tried to clean it if there is any dust but it looks clean.

Is this a hardware issue?

2

What says the log from the CRS? To which Version did you update and did you upgrade the firmware? Are you using the combo ports?

A bit more information would help a lot

3

The log only mentions the port shortly:


 2026-01-24 13:47:06 interface,info ether1 link up (speed 10G, full duplex)
 2026-01-24 13:57:22 interface,info ether1 link down

This was after I deactivated and reactivated the port. It worked for approximately 10 minutes and then failed again. Now it does not work at all and I use another port in the meanwhile.

Firmware is RouterOS 7.21.1

4

Did it start after updating the device or was it already before that?

Tested with an different device, that is connected to ether1 with different cable?

Try setting port negotation manually to 10 or 5 Gig

5

The problem appeared once before with an older firmware. At that time rebooting the switch fixed it and it did not appear again until today. Connecting another device and setting negotiation manually does not help. The lamps on the port flicker for a second but then stay off.

6

You could try to netinstall it.

If that doesn’t work, I would mark ether1 as defect.

7

I guess I will RMA it although I have read that it takes quite a long time. Maybe I am lucky and they just replace it because it is barely 2 months old.