Try manually selecting a network. Sometimes, even if you can't access Three's 5G network in a certain area, you should be able to access the 4G network. On most phones, it's possible to set your device so that it automatically chooses the best signal strength (5G/4G/3G). To find out how select a network, visit our Device Support area. Select your device, then go to 'How to manually select a network' under the 'Network section'. From there, follow the instructions.
If you're still experiencing issues, contact us at three.ie/contact-us/chat or here on the 3Community. We can check your area for any current outages or site issues, and can also check your account to ensure you are set up correctly for 4G and 5G data.
If you've checked all of the above and the issue persists, try your SIM in another phone.
If there are no issues on the other phone, this indicates a problem with your phone. You can get your phone sent for repair from any Three Store.
If you're still having problems with another phone, then you should get your SIM replaced from any Three Store.