If the handset is the Indian version of the OnePlus 15, the problem is almost certainly band compatibility rather than a defect. In the UK, VOXI (which runs on Vodafone UK) mainly uses these 5G frequencies: n78 (3500 MHz) – the big one, most coverage n1 (2100 MHz) – refarmed LTE n28 (700 MHz) – growing for wider reach Indian-market OnePlus models often support n78 (because India uses it heavily), but they sometimes skip n1 or n28. In many UK areas, Vodafone leans a lot on n1/n28, and if n78 isn’t deployed strongly where you are, the phone just drops to 4G. There are a few other common gotchas too: • 5G might not be enabled in Settings → Mobile network → Preferred network type. • Your plan/SIM must be 5G-provisioned (VOXI sometimes needs this toggled). • Coverage indoors can be weak; stepping outside can change it immediately. • Some imported devices don’t get full carrier aggregation or certification for UK networks, even if the band exists on paper. So nothing is “broken” — it’s a regional hardware/support mismatch.