RT-AC88u in ap mode (coming from 380.64 final /w nvram reset)
Well it seems Asus did a downgrade on wl version?
380.64
/tmp/home/root# wl ver
1.369 RC1.0
wl0: May 12 2016 11:14:24 version 10.10.69.6904 (r635567) FWID 01-c9c84353
380.65a3
/tmp/home/root# wl ver
1.363 RC45.58013
wl0: Sep 12 2016 13:26:39 version 10.10.69.6908 (r658761) FWID 01-5982b91d
The real version number to look for here is the 10.10.69.6908, and the r658761. That latter number is the version used internally by Broadcom on the source code itself (every file of the SDK has a similar revision number).
I have no idea what the first string refers to.
OpenVPN 2.4 in tun mode slower than on OpenVPN 2.3. Before upgrade I got 60-70Mbit (No cipher, no compression). After upgrade I only got 40-50Mbit.
Make sure you are REALLY not using compression or ciphers. The new negotiation protocol might have decided otherwise. The system log will tell you for sure.