I started experiencing this exact issue found in http://forum.mikrotik.com/t/sfp-port-flapping-rb5009-crs328-24p-4s-rm/173711/8 with a CRS310 after upgrading from 7.17.2 to anything newer, Auto negotiation just flaps back and forth indefinitely. I opened a support ticket as well and haven’t received anything solid back. This was a snippet from my last posting to the ticket (This was after experiencing this issue with 7.18, and 7.19):
I have some additional information regarding the issue. We upgraded to RouterOS 7.19.1 and encountered the same problem—auto-negotiation fails indefinitely. The only reliable workaround is to either downgrade to version 7.17.2 or earlier (where negotiation completes immediately), disable auto-negotiation or disable auto-negotiation, reboot the device, and then re-enable it. This sequence restores functionality.
However, any subsequent reboot requires repeating this process. Notably, this behavior is unique to the CRS310; all our other MikroTik devices negotiate line rates without issue. It’s worth mentioning that the CRS310 is the only device using MikroTik-branded SFP Ethernet modules. All others use DACs on the SFP+ ports.
The modules we are using are S+RJ10 (/r2 at the end of the serial).
Now I can easily disable auto-negotiation and this problem goes away, but up and to this point and for years with any other piece of Mikrotik hardware has worked without issue and I don’t see any reason why we shouldn’t keep using this feature. Now this run on ethernet cable is a little longer then most, but CRS310 has served us well for the last year and a half without issue until any version of ROS 7 greater then 7.17.2.
Has anyone encountering similar issues with the CRS310-8G+2S+IN or can suggest any settings that should be considered in newer versions of ROS 7.18+ to restore the stability experienced in 7.17.2 and lower?