iPhone Personal Hotspot
You can connect to a Personal Hotspot using Wi-Fi, Bluetooth, or USB.
Bluetooth: Make sure that the other Bluetooth device is discoverable. Go to Settings > Bluetooth to pair.
USB: Plug in your iOS device to your Mac or PC using the USB cable that came with your device.
When you connect a device to your Personal Hotspot, the status bar turns blue and shows how many devices have joined.
The number of devices that can join your Personal Hotspot at one time depends on your carrier and iPhone model.
If other devices have joined your Personal Hotspot using Wi-Fi, you can use only cellular data to connect to the Internet from the host device.
To disconnect a device, turn off Personal Hotspot, turn off Bluetooth, or unplug the USB cable from your device.
If you disconnect all devices from a Wi-Fi Personal Hotspot, it turns off automatically.
A user reports: I did have 5 connected to my 6 Plus and as I recall we could not add a 6th device.
JJR has connected 3 devices.
Set up Instant Hotspot
Use Instant Hotspot with any Mac, iPhone, iPad, or iPod touch that meets the Continuity system requirements. It works when your devices are near each other and set up as follows:
- Your iPhone or iPad (Wi-Fi + Cellular) has Personal Hotspot turned on in Settings > Cellular > Personal Hotspot.
Your device must have an activated carrier plan providing Personal Hotspot service. - Each device is signed in to iCloud with the same Apple ID.
- Each device has Bluetooth turned on.
- Each device has Wi-Fi turned on.
- On Mac, use the Wi-Fi status menu
in the menu bar to choose the name of the iPhone or iPad providing your Personal Hotspot 
.
- On iPad, iPod touch, or even another iPhone, go to Settings > Wi-Fi, then tap the name of the iPhone or iPad providing your Personal Hotspot .
If you're asked for a password when connecting, make sure that your devices are set up as described above. The Wi-Fi status icon in the menu bar shows the Personal Hotspot icon as long as your device remains connected to your Personal Hotspot.