This happened out of the blue, without indication of anything else being wrong. I just noticed that NFS stalled, and realized that the server is not on the network. The system on the box was running fine, but there were no lights on the network connector (it is connected with the upper, 1Gb, adapter). I replugged the cable into the 2.5G socket and it went online. Then I powered the box off and on again, with the cable in the 1G socket, and it came online normally.

This is what I found in dmesg/syslog:
 

Aug 31 09:31:39 localhost kernel: [379809.423687] NETDEV WATCHDOG: eth0 (rk_gmac-dwmac): transmit queue 0 timed out
Aug 31 09:31:39 localhost kernel: [379809.424506] WARNING: CPU: 2 PID: 0 at net/sched/sch_generic.c:468 dev_watchdog+0x398/0x3a0
[...]
Aug 31 09:31:39 localhost kernel: [379809.447941] rk_gmac-dwmac fe300000.ethernet eth0: Reset adapter.
[...]
Aug 31 09:31:39 localhost kernel: [379809.688895] rk_gmac-dwmac fe300000.ethernet: Failed to reset the dma
Aug 31 09:31:39 localhost kernel: [379809.689493] rk_gmac-dwmac fe300000.ethernet eth0: stmmac_hw_setup: DMA engine initialization failed
Aug 31 09:31:39 localhost kernel: [379809.690302] rk_gmac-dwmac fe300000.ethernet eth0: stmmac_open: Hw setup failed

Full log attached.

watchdog.txt

Hi @crosser, what Armbian version do you use?

Could elaborate what did you do with the NFS? Maybe you were doing big file transfer.

On 9/3/2021 at 6:56 AM, aprayoga said:

Hi @crosser, what Armbian version do you use?

Could elaborate what did you do with the NFS? Maybe you were doing big file transfer.

crosser@kobol:~$ uname -a
Linux kobol 5.10.60-rockchip64 #21.08.1 SMP PREEMPT Wed Aug 25 18:56:55 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux
crosser@kobol:~$ cat /etc/os-release 
NAME="Ubuntu"
VERSION="20.04.3 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Armbian 21.08.1 Focal"

Cannot really "elaborate" what I am doing with NFS, I just use it lol!  There was no special excessive data transfer at the time, to the best of my knowledge. And it was just one such occurrence so far, since I am using the device. It's not a problem for me (so far at least), I simply thought that it would be right to report.