I did a nvram erase and a full firmware recovery to 380.67 BETA1 and my Asus RT-AC5300U started acting all weird. First off, it didn't save any of the wireless settings from the "first-time wizard". Secondly the whole 2.4GHz radio didn't accept any connections/passwords, neither the actual SSID, nor the Guest SSID. It was impossible to connect, even changing to not have a password wouldn't let clients connect. 5.0GHz on the other hand seemed to work.
Enabling AiProtection and Adaptive QoS (Gaming) make Core 1 on the CPU hit 100% pretty much all the time, and the CPU temps was 102-103 constantly. Everything seemed to be working (besides 2.4GHz wireless) but my iPad Pro 12,9 Gen2 had some serious bandwidth issues when connected to 802.11ac WiFi, but my girlfriend's iPad Pro 10,5-inch and our iPhone 7 and iPhone 7 Plus did not have issues. According to Speedtest-app on my iPad I had 200ms+ and about 1 mbit down and 0,5 mbit up during testing and everything was dreadfully slow. Browsing was slow, ProTube/YouTube was constantly buffering etc.. All while my girlfriend could stream 1080P Netflix on her iPad without problems.
I tried to reboot my iPad but nothing helped. Tried a reboot of the router, but nope..
So this morning I did a new nvram erase and a full firmware restore to 380.67 BETA1 and this time around none of the awkwardness from yesterday occurred. The WiFi-settings from the first-time wizard actually sticked, the 2.4GHz WiFi and the 2.4GHz Guest WiFi are both working. My iPad is getting proper speeds and everything. Only difference this time around is that I have yet to enabled AiProtection and Adaptive QoS and I'm hesitant to do so in fear of it messing something up. If I recall correctly, I've had issues with both AiProtection and Adaptive QoS causing some huge CPU spikes in the past.
Another thing like always is that I can't get hardware acceleration level 2 aka CTF + FA working. Has Asus disabled FA all together in newer firmware's? Even right after doing a full restore of the firmware and not doing anything with the settings other than going through the first-time wizard I still only have hardware acceleration level 1 aka CTF and no FA. I tried various "tips" I found on Google, like disabling Spanning Tree Protocol, disabled acceleration, do a reboot and re-enable acceleration (while keeping STP disabled) but that still only gives me CTF and no FA.
EDIT:
This is is also the first time I use the Guest Networking option as I have never ending increase of various devices on my network that I don't see why they should have any intranet/LAN access at all. Like Withings/Nokia Smart Body Scale, Ring Video Doorbell etc..
But after testing the Guest Networking option I have a hard time understand what it really does? Other than creating a secondary SSID with its own security settings. There seems to be no VLAN involved as clients connected to the Guest Network still gets IP's in the very same DHCP-scope as the rest of the network and clients connected to the Guest Network is still able to ping other local clients and whatnot. All this is with the allow access to intranet option disabled.