Apple says the 6S can get up to 866mbps download on wifi. I just had Google Fiber installed today and the fastest speed I've seen was 500mbps download. While I'm not complaining, I was excited to see 800+, how am I supposed to see those speeds?
I wouldn't know on that. I use Comcast wifi and rent their modem. Down speeds vary from 65 to 88 Mbps. I would try another modem/router.