UART Config help needed - failed to init error

I am using a Banana Pi M2 Zero to control my 3D printer controller. It works perfectly running Armbian through the USB port but I need to switch to UART for 2 reasons. First I could not disable USB Otg so it's pumping voltage into the board and the display is washed out form the additional power. Second, it is impossible to use a USB cable because the USB port is only accessible from the outside in the steel enclosure.

I used armbian config to disable USB and then select UART 3 to use GPIO pins 8 and 10 but can't get it to work. I keep getting a Failed to init error

1. Is that all the config I need to do? If not what else?
2. The overlay in my config is active
3. How can I confirm the port is working? I did the Grep tty thing and it reports the following:

    0.000000] Kernel command line: root=UUID=e7e80086-a15f-4f2e-825d-9913c71ff19c rootwait rootfstype=ext4 console=ttyS0,115200 console=tty1 hdmi.audio=EDID:0 disp.screen0_output_mode=1920x1080p60 consoleblank=0 loglevel=1 ubootpart=bfca11dd-01 ubootsource=mmc usb-storage.quirks=0x2537:0x1066:u,0x2537:0x1068:u   sunxi_ve_mem_reserve=0 sunxi_g2d_mem_reserve=0 sunxi_fb_mem_reserve=16 cgroup_enable=memory swapaccount=1
[    0.000349] printk: console [tty1] enabled
[    2.223132] printk: console [ttyS0] disabled
[    2.223227] 1c28000.serial: ttyS0 at MMIO 0x1c28000 (irq = 44, base_baud = 1500000) is a 16550A
[    2.223478] printk: console [ttyS0] enabled
[    2.224699] 1c28400.serial: ttyS1 at MMIO 0x1c28400 (irq = 45, base_baud = 1500000) is a 16550A
[    2.224918] serial serial0: tty port ttyS1 registered
[    2.225722] 1c28c00.serial: ttyS3 at MMIO 0x1c28c00 (irq = 46, base_baud = 1500000) is a 16550A
[    6.072295] systemd[1]: Created slice system-serial\x2dgetty.slice.
[    7.196435] systemd[1]: Found device /dev/ttyGS0.
[    8.297021] systemd[1]: Found device /dev/ttyS0.

1. What is the name of my port? I assumed /dev/ttyS3. Is this correct?
2. What is Con3 on the board for? It looks like a separate dedicated Serial port but there is no documentation on it. Should I be using that?

Thank you!