Recently I upgraded my home AP. The AP is an Aruba AP555 and has worked really well so far.
After the upgrade things went haywire. A large amount of digging and searching finally led to the cause which was the more recent firmware set a default state for the secondary Ethernet port.
The original state was for it to default as part of a LACP/LAG with the primary port assigned to the Uplink. This works great as you can pretty much plug in both ports and get off to the races. The new firmware however defaulted this to Downlink. This caused all sorts of fun traffic routing issues that made absolutely no sense.
Image to come later...