I wonder if anyone else is seeing this behaviour. I'm running the stock LEDE 17.04.4 build, without any extra software installed, and for a while now I've been noticing that after a day or so of uptime (sometimes less, sometimes more, it has reached 3 days before crashing), the WiFi connection just deteriorates suddenly, until it actually crashes and no one can connect to it anymore. I have to soft reboot the router to get it all back.
The only log I could check, the kernel log, showed nothing abnormal. I tried seeing the System Log, but logging in into LUCI speeds up the crashing (it won't even log in), and I couldn't find in time how to output the system log to SSH because it was so slow, it eventually just stopped altogether.
I'm also not running out of RAM at all, and CPU usage was minimal during this sequence as far as I could see.