@MR.S 

thanks, i was genuinely starting to wonder if my port was going bad!

Luckily i have two links to my core switch managed with STP so usually the rj45 is blocked and is only used as a failover.

  @MR.S 

I have been using a generic SFP+ DAC cable, i have 5 of them, every single one works.  My port only goes down on a reboot, sometimes, not always.  Its not repeatable reliably, but the port is definitely not operational at all on some boot-ups of the router.

  @GRL 

I have a 10G Ubiquiti DAC going from my 10G lan to a 10G fiber port on a SZX3016F switch.

I have had no issues with my ports on this new firmware.  

  @MR.S 

It has only hapenned to me 3 times since the april 1.3.0 build.  I have restarted it a bunch of times when i first noticed the issue and 90% of the time it comes back up.  

Today it failed again - i manually turned everything off and unpliugged for our building electrical inspection.  When i powered up the whole rack, the port was off again.  Rebooted the 8411 individually, port was back.

I wasnt having this issue with the March 1.3.0 build

EDIT for the TP-Link people - this even happens on the router after a factory reset and zero configuration (either standalone or controller) - i tested this the first time i noticed the issue last week.

Managed to catch mine in the LAN2 SFP+ non-working state after doing a test power-cycle tonight

No weird configs on the port

Its just...off.  Disabling and Enabling on the port config screen doesnt get it to come back on.

It goes into port 28 of my 3428X - no link of any kind, no blinky lights on either end on the switch & router port LEDs.  Port 1 is my ER8411 RJ45 backup link, blocked by rSTP if the SFP+ link is up, so is now unblocked and active

At this point i tried physically disconnecting and reconnecting the SFP+ DAC cable at both ends - no change.  I changed the cable - No change.  I changed the switch port - no change.  It seems when its in this state the port is completely disabled on the router and will not come back up.

Then on a reboot of the router and no config changes of any kind............. the SFP+ is back up normally

port 1 on switch is being rSTP blocked again, as expected, port28 now has link.

Clive - i should have reported this a wekk ago when i first noticed (sorry) - but i think this needs attention ASAP - this firmware has moved into the "Release Candidate" section on controller, so its probably not too far off general release and being pushed to thousands of routers - and then users might start reporting this en-masse thinking their ports are dead!