PDP authentication failure on iPad

Hi.. My iPad is prompting an error 'PDP authentication failure'. I am unable to connect to the internet. iPad is an iPad mini 4 which was recently updated to OS version 10.3.2. Have already tried rebooting, removing sim card & rebooting, putting iPad on flight mode-removing sim card-rebooting-reinserting sim card-rebooting. Hope someone can help me on this. Thanks.