To whom It may concern:

We need your help.
Currently we are experiencing issues in our scenario. We use two MikroTik CRS326-24S+2Q+ switches: one with FW version 6.46.3 and the other with version 6.49

We are trying to negotiate a 40G connection to a server directly that supports it and we see traffic on the old firmware (6.46.3), but not in the switch with the newer firmware version installed (6.49):

Is “Autonegotiate” the correct setting?, or, or should we set it manually at 40G? (neither seem to come up with a link), both switches are connected to the same server with a dual adapter with the same settings. We get RX traffic but no TX traffic from the switch.

We are using a Q+DA0001 (https://mikrotik.com/product/q_da0001) between the two NICs on the server side and two CRS326-24S+2Q+RM switches.

We disabled qsfpplus1-1 for now so the interface stops flapping, we need it on for any kind of troubleshooting or getting the spifout file for support.

Did you try updating the Mikrotik-Device to the ROS 6.48.5 (Long-term) ?
Some Forum-Users seam to have Problem with ROS 6.49 and SFP /QSFP modules...
Maybe a Bug in the Version....

Hi!
Try the following:
( If the 1st is solve the problem, the 2nd one is not needed )

1., Disable / Turn off - all power-saving options on the Windows Server Network card:
"Allow the compter to turn off this device to save power"

2., Disable / Turn off - all offload options on the Windows Server Network card
"generic segmentation offload"
"TCP segmentation offload"
...