The router has to be next to my cable modem which is on the first floor. There are 2 floors above and one (basement) below. Signal is excellent on first floor, very good in basement and 2nd floor. Good on 3rd floor except behind a wall with no direct view to the stairwell leading down (and even in those spots its no worse than the 857, about -75 dbm on average). Most of the devices in that room are connected to the network over a 500 megabit powerline ethernet arrangement. The wiring to that room is relatively new so I get very good throughput (350 megabits on average). The only WIFI I use up there is on portable devices (phones and tablets) and the 865 delivers adequate signal and throughput to them for the most part. The 857 signal was definitely weaker.
This is an old house (circa 1965) with lots of separate rooms behind sheetrock walls. Almost no line-of-sight-to-the-router from any of them. At the moment we've only got a few devices that we're using on 802.11n. I used to have quite a few more that talked over wireless bridges, but I mostly replaced those with powerline ethernet. Pretty much all I have left using wireless is phones, tablets and one laptop. I believe all are dual band capable, but I think only the laptop supports 300 megabits. So yes, the 865 is overkill for the moment. I was mostly interested in the promise of better signal strength for the portable devices and that seems to have come to pass.
Yes, there is a reboot later option. Thankfully its not needed very often as most changes seem to be able to be applied on-the-fly. The 857 wanted to reboot after nearly every little change I made.
The QOS UI can be seen here:
http://goo.gl/MkE0VLooks nice, although it is not clear why I would need to use it. I have 60 megabits down and 8 megabits up and rarely have any bandwidth conflicts. I've left QOS off for now.
I'll try some transfers over the coming days and report back.
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bc