Ok, this is what I experienced too. In my case applying new firmware **seems to** have solved the problem. I can't tell 100% because there were situations where the switch resumed working even before the upgrade.
In your case, if even after all you did the problem wasn't solved, I would consider a hardware fault.
As a last resource, have you tried switching PoE off and back on?
Code: Select all
lanpower stop 1 lanpower start 1
Sorry but I don't know what else to suggest. Maybe the experts have more to say.