If you have a PC download WinFi Lite and that gives you all the info you need. Above screenshot from WinFi.Okay, then where do I find my AP uptime?
As for the comment by OP regarding the 41994 ‘beta’ (which was recommended by ASUS to all users), a new release is out for the RT-AC86U since April 28th, 3.0.0.4.386.42643 (Which for the ones running hot contains a fix, among others, for the high CPU usage and apparently temps are running lower again.
Thread 'New AC86U firmware 3.0.0.4.386_42643'