no parity and no flow control
if this board is similar to other models (AP3805i and EAP1200H)
it is likely that the RX line (pin 4) is connected to ground with a resistor
(see Adding OpenWrt support for Extreme Network AP3805i - #46 by akornow)
It is also possible that serial console is simply blocked by the software (and by software, it could be either pin muxing registers or missing "console=" in kernel command line), in which case the workaround is to downgrade the firmware and enable SSH
(see Adding OpenWrt support for Extreme Network AP3805i - #66 by akornow)
before you modify the board, you should share pictures of your board (or just tell us the FCC ID so we can look up pictures). You should verify the board designs are the same before ripping off any resistors.
(nevermind dont start a new post)