iPhone not connecting to local data networks while abroad.

My iphone 12 is not connecting to local networks while I am on holiday in Spain. Data roaming/Mobile data is switched on. Have tried switching phone off and updating latest software. When I go into Settings>Mobile Service>Mobile Data there is no option to do manual network search, only the option to switch between my Personal SIM and Business SIM. I only have data on my Personal SIM and I have checked my network provider account and I definitely have data available and data roaming is enabled. I can make calls and text messages but can't use internet unless I am on Wifi. Any ideas, people? Thank you.