There are a few issues that you all need to fix for reliable WiFi on Apple iOS products:
- Make sure your wireless router has both 5GHz (802.11a/n/ac) and 2.4GHz (802.11b/g/n). If it is a b/g or b/g/n only router, go get a new one.
- Make sure both Apple device and Wireless Router are both patched with up-to-date firmware
- MAKE SURE YOUR 2.4 and 5GHZ SSIDs ARE DIFFERENT!!!!! IF NOT, YOU WILL HOP BANDS AND LOSE WiFi Sporadically! Most people just add 5G to the 5GHz SSID, i.e. BobsWiFi for 2.4GHz and BobsWiFi-5G
- Make sure your WiFi router is set to WP2/Personal with AES. Do not use WEP or WPA with TKIP.
- Ensure that both AES and TKIP are not allowed at the same time, this confuses Apple iOS devices. Only AES should be allowed
- Connect to the 5GHz only SSID when possible. 2.4GHz travels further through obstructions, i.e. walls, than 5GHz, but has many interferers such as PlayStation, Xbox, and Roku remotes, Bluetooth devices and Microwave ovens. There is also many less channel options for your router to choose from, 3 channels, so you will always have tons of interference from neighbors in metro areas.
- Connect as many of your home devices to 5GHz only as possible. This will ensure that the devices that must use the 2.4GHz (b/g/n) frequency work best.
- If you can tolerate it, need less that 130Mbps WiFi or internet package is less than 130Mbps anyway, use a 20Mhz channel on 5GHz. The wider the channel, the less options your wireless router has to find a channel without interference. That being said, if you live in rural areas with acres of land between you and neighbors, this likely doesn't apply to you. You wouldn't have to worry too much about interference from your neighbors, so set your WiFi router to auto 20/40/80 for 802.11ac or auto 20/40Mhz for 802.11a/n and enjoy.
I am a network engineer, and as such know what basically every wireless supporting network engineer does when it comes to Apple products; They are some of the most well put together devices on the planet, are very stable and user friendly, but are much more finicky when it comes to WiFi performance. You should have fairly stable WiFi as long as you follow those steps outlines above. As with everything, you get what you pay for with WiFi routers. If you buy a new $800 iPhone and a less than $50 wireless router, you may have a lot of pain with home wireless. I have had a lot of luck with replacing lower end b/g and b/g/n routers with several brands of 802.11ac routers and yet to be burned. $80-$110 is typically the sweet spot these days for getting a quality product. I would say Netgear, Linksys, and Asus all have great products in this range. You can also look at Apple for wireless, but I don't recommend if you don't have an Apple device centric household.