Q: Slow Wifi on iPhone 6 Plus

Thanks so much Mikef91!  I have been ready to throw my new iPhone 6 out the window.  So far your suggestion has worked.  I'll report back if it stops working later.

Try switching off your bluetooth. The Wifi speeds up instantly for me.

I wonder if this is the problem they had with Macbook Pro a while back where if you have the bluetooth on the wifi stop working.

It's not so much IOS8, but the problem started when I got the Apple Watch and I have to left the bluetooth on all the time.

Can someone else confirm if it's the bluetooth interfering

Hi all, I have a brand new iPhone 6s Plus since updating to IOS 9.0.2 WiFi is very very slow. So much so that trying to even install twitter is taking over an hour. So I decided to test with Telegraph 4G which I have full speed and it is also very slow. I believe it could be a fault with the WiFi and LTE chips which if I'm not mistaken could be now in the A9 processor. Not sure IOS patch may fix this problem but need Apple to respond.

Yes very slow.  Reset my network settings and worked for a few minutes, but now it's really slow again.  I'm getting 18 mbps download speeds which isn't LTE fast, but it should be fast enough for downloading apps.  This has to be an iOS 9 issue.  I sent feedback to Apple about this problem so hopefully they'll fix it soon. 

FWIW after trying a ton of the suggestions in here, the one that just worked for me was to create a separate network name (SSID) within my router for the 5Ghz network. Once my two problem devices (iPad Air, iPhone 5S) were forced to connect to that 5Ghz-only WiFi SSID, BOOM, problem solved. Router is an older Airport Extreme (Fifth Generation).

My symptom had been as follows: iPad Air 2 and Android phone operating on WiFi at expected max speed given our Comcastic plan with an owned DOCSIS 3 cable modem (about 50MB down)... meantime my iPhone 5s and iPad Air painfully slow (like under 1MB down). Occasional bursts of speed, but not for long. This problem only cropped up after iOS 9, which aggravates me. My suspicion is that it's something in iOS 9 on these older devices that makes it lock on to the 2.4GHz band rather than automatically using the more-robust 5GHz band. I should also say, for anybody reading this, I live in a crowded urban environment with a TON of neighboring 2.4GHz networks stepping all over each other (if you're a PC user curious to see this what your area's WiFi networks look like, try out the free Xirrus Wifi Inspector, pretty interesting). I bet if I lived in the country I wouldn't have experienced this problem.

Anyway, hope this helps somebody out.

Unfortunately, I am having the same issue, on all my Apple devices with IOS 9. Use speedtest app and get 12 ms ping, 20mb download and 12mb upload. It has to be the operating system. All apps that require connection are sluggish or even freeze.

I have the exact same problem. Wifi speeds are fine on speedtest (30+mbps); however, all apps, including apple store, games, browser, etc, all super slow on wifi. Switching to LTE immediately solves the problem.

*found solution finally*

I tried all solutions given above, everything is temporary.

The actual problem is the icloud drive. It uses a lot of bandwith, so switch off your icloud drive and your wifi will give you the best speeds.

I tried all kinds of things listed here but what seems to work the best is turning off bluetooth. My iPad has had no problems and I keep the bluetooth turned off.