See here, HW description bulletpoint 17 https://www.hardkernel.com/shop/odroid-m1s-with-4gbyte-ram/ Maybe it is also available on the 40-pins or 14-pins I/O headers, so a simple generic USB serial cable with jumper wires can be connected.

@SteeManI partially agree with you. So far, that you say, that people like @Igormight have more important things to do, than to answer (apparent) n00b questions in forums and I also agree that it is highly important, that there are more volunteering people who try to contribute. But on the other hand I think, that the perspective of you and many other "higher" developers (not only at Armbian) shifts with the level of expertise. What I mean by that is, that when people like me want to start to contribute, we have very limited knowledge in many fields. So many things are mysterious and sometimes we don't even know what we should look after or what we should search for when problems occur. You are right, that many questions arise regularly and sometimes this is annoying and a reference to the documentation is totally appropriate! But I have the feeling, that particularly here at Armbian, the demands for a question to be posted is very high (compared to the knowledge that beginners come with). And it happens VERY often, that it feels like a slap in the face when I have the courage to ask something and I get told "please stfu, here's a link to the source code." And I can tell you, that it is exactly this behavior, that brought me to the point, where I thought "well, f**k it. I just wait for my problems to be solved by others, if my request for help to help myself is treated like a request to get my b**t whipped for free". I've felt this quite often here. But I am STILL here, because Armbian is important to me - not only as the OS of my choice, but also as a project that is worth to be supported! But you should also know, that the willingness to contribute (as far as a n00b like me can) will go down rapidly, when you get slapped often enough. And to complain, that people don't want to contribute after slapping them is not fair. After that said, there the main topic: I was able to build Armbian with vendor kernel and extensions. I did this by adding the corresponding options to the build command. In my case, my build command looked like this: ./compile.sh build BOARD=odroidm1s NO_HOST_RELEASE_CHECK=yes KERNEL_BTF=no BRANCH=vendor RELEASE=noble BUILD_DESKTOP=yes DESKTOP_ENVIRONMENT=gnome KERNEL_CONFIGURE=no BUILD_MINIMAL=no DESKTOP_APPGROUPS_SELECTED='browsers internet multimedia desktop_tools editors' ENABLE_EXTENSIONS="v4l2loopback-dkms,mesa-vpu" First of all, I hope that this was the correct way to do it. Because my other option would have been to modify the board config file. But that didn't feel right... The problem now is, that the board just does not boot. After waiting some time the board falls back to the system I have installed on eMMC. Using another non-vendor system on SD card works. I have the feeling that there is something wrong between u-boot and the vendor-image. Maybe the vendor kernel image expects petitboot and does not work with u-boot? Is there a way to proof that (without overriding u-boot with petitboot)? You see... n00b question AGAIN. But I try to come as far as possible on my own... Cheers and have a very nice and joyful xmas season!

Actually, I was able to find that IC but in chinese version.. https://datasheet4u.com/datasheets/I-CORE/AiP1628/1571692 Looks like its some kind of low level chip that probably transforms low voltage signals into higher voltage, like the ones used on ethernet ports. Probably to power up the LCD leds.

I see now. Mine does not have those: I suspect those are some extra functionality that the chip marked as AIP16R (on the top) has but was not implemented. The OP's board maker tought it would be nice to make them into pins in the board at the very least, while my board maker simply left them unconnected. I was not able to find the specs for that AIP16R chip.

To get the ethernet working you have no option but to build an image with kernel support for mae621. See these posts :