I recently had an issue with my Netgear R7800 where nothing was able to connect, either wirelessly or over ethernet. Current circumstances made it difficult to troubleshoot during the daytime so I opted to replace it with a set of TP-Link Deco S4s. Easy enough to set up at a basic level but lacking many configuration options (for example using pi-hole with a Deco network is not straightforward) and features (other local clients are not accessible by hostname).
Since that time, I did a factory reset on my R7800, which didn't help with the problem I was having. I then did a fresh reinstall of openwrt which seems to have fixed the problem. (This makes me think that maybe maybe some corruption of the installed firmware occurred.) Everything seems to be good now but I wanted to see what others' experiences with the R7800 were like. I guess my biggest question is, could it be that my R7800's flash memory is failing and that I might expect similar failures in the future? I would be shocked if that were the case since mine is less than 8 years old (the flash memory on my original Linksys WRT-54G still works).
The one thing most often failing of all routers is the power supply.
When having strange problems e.g. spontaneous reboots, intermittent wifi problems etc. then try another power supply
But, the oldest of these routers are approaching 9 years of age, ran continuously and considering the relatively high operating temperatures (>60°C), it is only to be expected to see the first hardware failures by now (also on the analogue side of the wifi cards). While I wouldn't consider it to be a general issue yet, chances to get hit by hardware failure (beyond the easy PSU replacement) are likely to increase.
Depending on your environment (climate/ air humidity), you might also observe corrosion on the PCB, as we've recently seen in a post about a Linksys EA8500; tropical climates or salty environments near the sea are a killer for any kind of gear.
Neither tropical nor near the ocean. It's been running for over 24 hours now with no issues but not under a production load. I guess I should put it back under production and see how it goes.