Netgear D6400 wired devices stopped working

Had this router for just under a year and no issues. However 10 mins ago all wired devices attached seemed to disconnect, no data was passing to them. wifi devices remained connected and data was passing through to them. Checked in the router device list and noticed no wired devices attached, however all wifi devices were fine, and checked them all and were working

Rebooting the wired devices didnt fix it, so needed to reboot the router which appears to have worked. Anything in particular that could have caused this? First time ive ever encountered this

Have you updated the firmware in the last few weeks? It could be a memory leak in a process that eventually exhausts all available free memory. If you haven't updated it recently, perhaps it's time to because the instability may apply to earlier firmware.

If you look back at Netgear's downloads it seems that there have been occasional stability issues with certain version of firmware. That's the first thing I'd look at.

No not updated firmware for months. Although looking on the website it appears a few minor updates have come out but release notes only mention security updates and not fixes. Will try that tho

Uptime was 40 days before this issue, but same firmware ive had 100 days uptime without a reboot and no issue

Apply the firmware updates ASAP and see if the problem reoccurs. With pending security updates the fact they are not applied means your problems could be down to a bad actor probing your insecure router.

If the wireless router still had working Wi-Fi and Internet that suggests only its integrated switch was affected.
If so, either the switch locked up and stopped responding to rest of router, or the switch glitched out into a state where it thought no wired links were up.

I haven't checked whether this model has per-port LEDs (maybe not) as that can usually be a clue what state it is in.

It's not possible to be definite about the cause unless something was written to the log to help identify that.
Either the router itself or client device could have generated some traffic which the switch could not cope with.
From a source on the Internet, as far as the switch is concerned that's the same as coming from the router.

Depending on models and firmware, some routers can implement a watchdog to check for integrated devices that aren't responding such as modem or switch, and re-initialise.
But consumer routers and firmware development are done to a price point.

Yea doesnt have LED lights for the ports. I couldnt even log into the routers homepage using the PC though, as it wouldnt recognise there was any link there. Had to do it on my phone when connected on wifi