I have an RB5009 that has a 10Gb fiber connection to the router in the main rack.
I recently upgrade to the RB5009 because of the 2.5 Gb port and my new comcast device.

Since then, the connection between that device and my CRS317-1G-16S+ is dropping and re-establishing many times.
I recently upgraded everything to 7.2.3 and I thought it had resolved it but it is happening again.

I have just changed the connection speed on both ends to 1gb in hopes that it will help.

Both SFP+ are from the same manufacturer.

This has improved in recent firmware, including the latest 7.3beta40. What are you running?

I am currently running 7.2.3.

7.3beta40 made it worse. I need to back rev now.

Did you set the port speed explicitly to 2.5G, autonrgotiate off, making use of the new feature?

If so, which SFP+ module are you using?

This has gotten so bad that i had to run an ethernet cable between two of the switches just to keep network stability.

Need to put a ticket into them.

I replaced RB4011 with RB5009 and I get rapid flapping with 1G Mikrotik BiDi modules.
Only if I set them to 1G - when set to auto negotiate, they do not connect at all.
I have a new 70m cable there (old one got damaged) and in the meantime upgraded the router.
Signals are fine, from -4,7 to -6 dBm, similar to previous cable.
Firmware is now 7.15rc2 - no change.
Tried to put it out of bridge, disable RTSP, restarts.
Other side is HEX POE and that is rock solid.
I can swap the modules and worst case put the 4011 back.
Is it known what is causing it?
There are some mentions in Amazon review that this is happening on them.