Netgear R7800 enters boot loop in LEDE but works with official firmware

[hnyman]

@Baud

is everybody using custom builds and leaving the “stable” builds for the R7800 unstable, or does mine have a hardware fault, or is there something else going on?

At least my own custom build (the community build linked above) are fully reversible, as they do not modify/extend the flash size. You could try either master or 17.01 build.
Build for Netgear R7800

I have flashed my R7800 over 300 times and have seen a bootloop only a few times, and that was due to testing kernel 4.9 patches (so that it was known beforehand that something may be wrong). Then it was some memory or bus timing error, which the core devs eventually fixed.

There has been something similar with WRT3200ACM lately, where the manufacturer has quietly changed the flash chip to a new model from Winbond that is not yet fully supported by upstream Linux. So, it is possible that the hardware the new R7800s is incompatible. But as your device initially boots ok, that is not that likely

The best way to analyse that kind of bootloop is to open the router and attach a serial console cable. Then you can follow the early kernel bootlog from a terminal. It is not complicated but requires opening the R7800:

Netgear R7800 exploration (IPQ8065, QCA9984)

Advice on opening Netgear R7800 case and using the serial console The case bottom and cover are attached to each other pretty tightly, but the case can be opened once you figure out all necessary steps: The circuitboard is attached to a heatsink that is attached to the top cover. So the bottom panel (with sides) is the one to separate from the others. The heatsink is likely attached with a thermal paste or such (I never removed it). There are five screws (Torx T-10) on the bottom that need to …

EDIT:
Well, I read your description again, and your problem is not actually a boot loop during boot process, but a crash later. Analysing that is a bit easier.

You could start the the router normally, and right after the boot, before you start configuring, open two ssh terminal windows on the side, and then monitor kernel and system logs there. Depending on which driver the crash happens, you might be able to see some errors and crash dump. You might then be able to identify. which driver causes that.

logread -f

But it is possible that there is some hardware failure, e.g. a faulty RAM chip.

Ps. the "clean flash" advice looks overly complicated. As all settings in Openwrt/LEDE are stored as files in the same partition, flashing without keeping settings clears the settings.