Hi @cpatsianotakis looking at:
https://elinux.org/Beagleboard:BeagleBone_cape_interface_spec#UART
P9.21/P9.22 isn’t available… i’d cut P9.21 header and bug wire it to P9.24 and cut P9.22 header and bug wire it to P9.26
Then load this overlay:
Which is pre-installed on these images:
Regards,