According to the datasheet (https://de.scribd.com/document/948890791/MT7988A-Datasheet) the supported baudrate seems to be between 300baud and 3Mbaud. However cannot tell anything about support status. Neither do I have this hw, nor did I ever dig into this soc. Starting with device tree overlays might be a good start or check the whole device tree in general for the uart nodes if present.

There is no such board. There is either Orangepi5 plus or Orangepi5b. Check your hw what you actually have. If there is indeed a "Orangepi5b plus" then it must be fairly new and is totally unsupported.

logs? versions??

I managed to boot armbian from SD card without eMMC. The way achived this is by create a bootable insomwrt with venodr u boot, using my script `./run.sh custom` then replace the ROOTFS with armbian's ROOTFS from there I could boot armbian and fix the fstab. So far it's working fine root@aml-s9xx-box:~# lsblk -f NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS mmcblk1 ├─mmcblk1p1 vfat FAT16 BOOT 1C34-0D25 200.9M 18% /boot └─mmcblk1p2 ext4 1.0 ROOTFS 6f2edfb1-adb2-4f1b-8087-46d189763c9b 5.2G 20% /var/log.hdd / zram0 root@aml-s9xx-box:~# uname -a Linux aml-s9xx-box 6.1.66-DBAI #1 SMP PREEMPT Fri Nov 29 09:52:27 +07 2024 aarch64 GNU/Linux root@aml-s9xx-box:~# uptime 01:44:24 up 19 min, 1 user, load average: 0.00, 0.00, 0.00 root@aml-s9xx-box:~# cat /etc/os-release PRETTY_NAME="Armbian 26.2.0-trunk.563 trixie" NAME="Debian GNU/Linux" VERSION_ID="13" VERSION="13 (trixie)" VERSION_CODENAME=trixie DEBIAN_VERSION_FULL=13.3 ID=debian HOME_URL="https://www.armbian.com" SUPPORT_URL="https://forum.armbian.com" BUG_REPORT_URL="https://www.armbian.com/bugs" ARMBIAN_PRETTY_NAME="Armbian 26.2.0-trunk.563 trixie" root@aml-s9xx-box:~#

Looks like only one HDMI port and one NVMe drive bays work on the edge kernels. Not sure whats wrong with HDMI port but two SSDs installed cause issues PCIE addressing. Probably overlay issue with the newer kernel images?