Yeah been meaning to comment here, after a longer period of stability on the beta firmware they provide I was back to the exact same error again. They agreed to give me a NIB replacement (new in box) last week..Couple updates from my side.
First, I got another Kernel panic last Monday ~14h after reboot, which is definitely bad news indicating that even everyday reboot will not guarantee 100% reliability.
Second, ASUS released another firmware, but this is rather neutral since there is nothing specific about this particular issue in their changelog.
And the last, but not least, @RMerlin released 386.5 firmware with added support for our model!
So I went ahead and checked out sources, searched for brcmnand.c files and found one with BUG_ON call in line 1339, which essentially triggers panic.
As I mentioned above, the reason for this is NAND controller reports itself as not ready 100ms after previous "read_page" operation, but I also found following commit in the link, provided by @strunker :
mtd: nand: brcmnand: Change BUG_ON in brcmnand_send_cmd · torvalds/linux@422485d
Change the BUG_ON() condition in brcmnand_send_cmd() which checks for the interrupt status "controller ready" bit to a WARN_ON. There is no good reason to kill the system when this condi...github.com
Decided to give it a try, spend couple of hours to setup wsl-based build environment and created firmware with above change applied.
Flashed it today, disabled reboot scheduler and crossed my fingers.
Obviously, it might not help at all, since if it really problem with NAND controller gets stuck - router will lose ability to read/write from/to NAND, but at least it should not panic/reboot right away anymore.
They wrote back today so state they have none in stock and arent sure when they will again, and that they would offer me a buy back instead. So I am kind of really.. stuck here. I dont want to flash on merlin for testing and then void any type of buy back they would otherwise be willing to do. I am an engineer for a living, but I wasnt really wanting\expecting to have to do all that just to get a 600 dollar piece of equipment to work properly.
Not entirely sure where to turn would REALLY love to try the newer gt-axe16000 mostly cuz it has 10gb lan ports, but I have no concept of how long of a wait that is going to be before that becomes available. May have to dump Asus all together and go with something else, maybe ubiquity?