Hi @JacekJ    We did check the logs in Switch 2 and specifically the same time (around 2am) that the port which links the switch 1 & 2 was disabled on Switch 1 and there were no entries. Here is the log from Switch 2 - the events starting at 6.50am were from when we rebooted the switch to be able for the port to come back online. Thanks, Stuart ... View more

Thanks @DarrenOC @JacekJ  - apologies for the delay in coming back to you...been on Jury Duty the past 2 days! Thanks for your explanation....I think this is how we have everything set up APART from the port connecting to the Cisco router.  It is set to Loop Guard so I am thinking this should be changed to Root Guard as we do have VLANs running over the connection. Here is a pic to show how we have the various ports setup - from what I can see this matches your explanation I think!   If you agree this is set up correctly then I think the next steps would be to change the port which connects to the Cisco and then potentially change the cable connecting the two switches where the port is disabling???  Would you agree?   Thanks, Stuart ... View more

Thanks @DarrenOC    Yes our Cisco router is connected to Cab 1 Switch 9.   So to confirm you would set the uplink port that the router is connected to as Root Guard and every other uplink port (across all switches) as Loop Guard? ... View more

@DarrenOC  - I thought a drawing might help here.  I am thinking from your comments we are maybe missing some settings for the other switches? ... View more

Thanks - will give that a bash...just seemed strange it would happen in the middle of the night with little to no traffic. ... View more

Hi @Brash, the port is connected to another switch so when the port disables it affect that switch and then the other 3 below that (they are daisy chained).  When I look at the second switch and check the event log there is nothing relating to the port it is uplinking too.   Thanks   Stuart ... View more