Internal Serial Console Connection?

Hi Gents

I am on the whole very happy with my Argon Eon, The fan never needs to come on and I have 2 x 7Tb SSD’s and 1 x 8TB 3.5" drive.

However when I do a large file transfers over Wi-Fi the Wi-Fi on the Pi4 locks-up and I need to console on to the Pi to reset the Wi-Fi. I am already using the rear GPIO port so I’m hoping there are spare pins inside to attach a serial cable rather than the external rear GPIO pins (again I’m using them).

Does anyone know what these internal pins are for?