BT Italy APN Settings for Android 6 Marshmallow

Go to Settings More / Mobile networks Access Point Names

Press ➕ on right top

Name: BT
APN: Internet.btitalia.it
Proxy:
Port:
Username:
Password:
Server:
MMSC:
MMS proxy:
MMS port:
MCC: (keep the default value set by phone)
MNC: (keep the default value set by phone)
Authentication type:
APN type: default
APN protocol: IPv4
APN roaming protocol: IPv4
Bearer: Unspecified
APN PPP phone number: Not set

Do not change the default values set by device for all blank fields above.