I had a bit of a hiccup on my rt-ac86u running a dirty flash from 384.19.
Router simply stopped routing to the Internet suddenly. No log messages, and no other issues seemed evident, all WiFi and services seemed to be running. The only sign (other than the lack of Internet) that the router was misbehaving was that I got the message about the 150 outstanding DNS request limit having been reached.
The only addons I am running are cake and ntpmerlin. Trend permissions are revoked.
I'll keep an eye on it to see if it happens again, and if it does, I will do a factory reset and start fresh.
In general though, I have noticed that 386 is seems to grab more RAM than 384 did. My RAM usage will start at around 60%, then climb steadily to 80%(ish) over a couple of days. On 384, it would climb, but much slower, and not to that high a value.