O2

I have a sim card in a wifi router on a boat 200 miles away which I use with a surveillance camera.I buy data each month but I have just tried to log into the account and it is advising me that as additional security it has sent a code in a text mess...

I have a Samsung Galaxy A12 which is a 4G phone but when I go to 'settings/mobile networks/network mode', I can only set it to 2G or 3G.