Your post has been moved to a dedicated new thread, it doesn't seem related to the longstanding issue in central Oxford.
Use the "check service status" option on https://ee.co.uk/help/mobile-coverage-checker in the first instance, to check for local service outages. The "report a problem" link should be used if no issues are reported but EE users continue to have issues.A loss of coverage will remove the ability to make/receive calls, send/receive texts or use mobile data.
A 5G device should fall back to 4G anytime there's no 5G coverage, unless 4G is also affected by the outage and there's either no-coverage or only 2G.
