No. An internet connection is only required to download your mobile ticket(s).
You will not need an internet connection to enter the stadium once you have downloaded your mobile tickets on your phone.
So make sure you open the app at least once before arriving, in case it needs to update.
You will need your phone to be charged and have Bluetooth on.
However, an internet connection is needed to transfer your ticket(s) to your guest(s).
We therefore recommend transferring tickets before heading to the stadium as the connection onsite might be limited.