I have problems on 30% of the boards.
It connects briefly, three times to gigalan, and then connects at 100M
As if for three tries it connects, but then fails to maintain the connection.
It could also be a PCB layout problem, but is there any advice on how to solve this via software?
It appears you are using firmware that is not from the official OpenWrt project.
When using forks/offshoots/vendor-specific builds that are "based on OpenWrt", there may be many differences compared to the official versions (hosted by OpenWrt.org). Some of these customizations may fundamentally change the way that OpenWrt works. You might need help from people with specific/specialized knowledge about the firmware you are using, so it is possible that advice you get here may not be useful.
Ask for help from the maintainer(s) or user community of the specific firmware that you are using.
Provide the source code for the firmware so that users on this forum can understand how your firmware works (OpenWrt forum users are volunteers, so somebody might look at the code if they have time and are interested in your issue).
If you believe that this specific issue is common to generic/official OpenWrt and/or the maintainers of your build have indicated as such, please feel free to clarify.
If it is a hardware problem, it needs to be solved in hardware. Software is not going to change that.
The problem you are describing does not sound like it is related to openwrt given that you are developing custom hardware. Iād recommend getting proper Ethernet test equipment to help you diagnose (or rule out) the specific hardware issues.
Are there any commands to help understand the problem?
To measure parameters?
Are there any registers to vary some parameters?
Amplitude, frequency.
There was talk of a bug, in a hardware version of the chip, but I didn't find it.
The products are ready to ship.
I will review the hardware in the next batch.
Can anyone help me?
Are there any Ethernet commands that give me in-depth debugging?
Where can I find the Ethernet registers?
I believe there is an MT7530 subchip inside the MT7621D CPU
Because this is hardware under development and nobody else has one of these units to diagnose the issue, you are the only person who has any way of making progress towards resolution. It is, therefore, a problem that you must solve on your own - it is not appropriate for you to ask the community to do your homework for you.