Sorry to bring up an old thread but I have just purchased a Hap AC3 with the external antennas and it still has all the same problems that existed from 3-4 years ago.
Sorry you only have yourself to blame, especially because you have prior experience. Most first time users tend to buy blindly and although they do they talk to friends, check out youtube, check out reviews we tend NOT TO CHECK OUT the biggie, the most IMPORTANT SOURCE, and by that I mean visit support forums to get a lay of the land --> well until they have bought the product and run into problem. So yes, the first time user gets a break but not afterwards.
No one here I know of with their head screwed on straight is recommending FOR A WIFI focussed requirement, wifi5 from MT. Granted their newer products hapac3, audience etc seem to be a less proprietary product and have better functionality (speed and stability) then the older wifi5 devices, but they do still have some issues.
BPWL is best suited, tracks this stuff closely, to state whether the hacac3/audience are indeed as good as other vendor wifi5 products and if better than older mt wifi5.
In any case, any moron that buys WIFI5, when there are now cost effective wifi6 options out there, is beyond help. The only reason to stick with MT wifi is twofold.
a. un paralleled flexibility of the RoS firmware
b. amazing capsman controller for those with many many wifi device.
Hence there are many here begging MT to provide some wifi6/6E etc RoS capsman capable devices!!!! ASAP!!!