This is based on mines, running Armbian Trixie: - NM can work without dhclient, it has it DHCP internally as well. So maybe look at that instead of AI with old info and certainly no clue about a specific SBC - modern kernel it is end0 - systemd-networkd is also an option - you also might use ifupdown still, also not needed, NM can do internally as well

Mine does not have any pinholes near the lcd display. Send a pic, or/and trace their paths into some chip and see what that chip does by its id

Here is my findings and solution. Hope this also solves your problem. When the network hangs, I can see that IPv4 address is lost using "ip a" on the console. I then check "journalctl -b -e" for logging and obviously it's a consequence of dhcp4 failure. Dec 19 22:54:10 pbsbc01h3 dhclient[4720]: DHCPREQUEST for 192.168.2.190 on eth0 to 192.168.2.55 port 67 (xid=0xb07e1eb) Dec 19 22:54:10 pbsbc01h3 dhclient[4720]: DHCPACK of 192.168.2.190 from 192.168.2.55 (xid=0xebe1070b) Dec 19 22:54:10 pbsbc01h3 NetworkManager[5189]: <error> [1766156050.2239] dhcp4 (eth0): error -111 dispatching events Dec 19 22:54:10 pbsbc01h3 NetworkManager[5189]: <info> [1766156050.2243] dhcp4 (eth0): state changed bound -> fail Dec 19 22:54:10 pbsbc01h3 NetworkManager[5189]: <info> [1766156050.2248] device (eth0): DHCPv4: trying to acquire a new lease within 90 seconds Dec 19 22:54:10 pbsbc01h3 dhclient[4720]: bound to 192.168.2.190 -- renewal in 288 seconds. With the help from ChatGPT, I modify "/etc/dhcp/dhclient.conf" with the following and the problem is gone. timeout 5; retry 60; reboot 10;

I am not sure if this will lead to problems. The SBC is a Radxa ROCK3A. It might be EVB was used for development and never changed. Maybe won't matter as later on kernel rock-3a dtb is loaded. But could be a reason for issues I saw (year ago) with mainline u-boot, therefor I use Radxa's one / legacy.

Maybe. If it is better you'll have to see. Install package 'linux-u-boot-rockpi-4c-edge' and with dpkg -L linux-u-boot-rockpi-4c-edge you can see where the u-boot binary is located, then: strings <u-boot binary> | grep armbian