This entry is from the time when the device been connected to the other AP (which presumably routes through the SG300)
And then
when the device roamed to the TO’s AP.
The problem is that the TO’s switch is unaware of upstream interfaces as neither DSA driver or the bridge driver appear to be communicating with
The ATU is only aware of the switch’s downstream ports, thus once a client roams to a port upstream of the TO’s switch the switch does not know what to do with the packets (does not have connection tracking) and drops them and therefore
until the ATU’s ageing period clears the client’s MAC. This user leverages a workaround