Sir, could it possibly be that you have a better router hardware wise? If I can plug it into the very spot my 66 was in and it has problems.....I doubt its my environment....I'm not the expert you are...and I don't have the money to throw down on every 300+ dollar router....but I think it should at the very minimum plug and play with ASUSs last gen routers.....I think these have hardware tolerance or quality issues.
Wireless networking will never be just plug and play, due to the fact that you have a bunch of different manufacturers trying to inter-operate with one another. Too many variables, and as wireless technology becomes increasingly complex with the addition of MIMO, MU-MIMO, 802.11ac beamforming, proprietary beamforming and so on. Take the Intel AC7260 just for an example that's totally unrelated to Asus. Under Windows 8, it took 6-10 months for Intel to provide a driver that worked properly regardless of the router that was at the other end.
Another case: it seems that every now and then, a new iOS release causes wifi issues that get posted all over the Apple forums. Many iOS 8 users reported issues with their iDevices.
Take such wireless interface issues, combine them with router-specific issues, and you get the current situation: wireless technology is one big messy situation of random luck on whether one particular router, with one particular wireless client, running in one particular environment, will be able to work properly "just plug and play", or if you will have to spend a lot of time upgrading router firmwares, wireless client drivers, changing channels, changing channel bandwidth, retiring that old wireless baby monitor, and so on.
That's why I always tell everyone, both on forums and my own customers that wireless should be a LAST RESORT technology, not a "let's go wifi everywhere". because it's very, very rarely "just plug and play". Ethernet will always work better and be far more reliable than wireless, because the technology is far simpler, with fewer variables.
These types of complains are far from unique to the RT-AC87U. I read the same type of complains from R7000 owners too. And every now and then, an Asus customer will switch to Netgear and claim that all his issues "just went away". And on another forum, it's a Netgear user who switches to Asus and claim the same thing.
So in short, people too often put all the blame on their router's firmware when a lot of times the actual issue lies at the client's end, or with their un-optimized router settings (how many times must people be told that using 40 MHz on the 2.4 GHz band is very unlikely to end up well?). When working on a wireless issue, the ENTIRE network must be looked at, not just the router. The "this other router works just fine" conclusion does not lead to any legit conclusion until they have actually went through the whole troubleshooting process.