The £135 price gap buys you 250 m² of extra coverage (500 vs 250 m²), 3 dB more gain (75 vs 72 dB), 3 dBm more output power (23 vs 20 dBm), 5+ extra simultaneous users (30+ vs 25), and a 10 dBi directional Yagi instead of an 8 dBi omni. If your premises are under 250 m², the C250 is better value. If you're at 300–500 m², the C500 replaces what would otherwise need two C250 units — at £399.98 combined, the C500 is the cheaper and cleaner option.

Up to 500 m² (5,382 sq ft) under ideal donor-signal conditions. Real-world coverage depends on wall construction, floor layout and interference. Open-plan barn conversions with steel portal frames often perform at the rated area; thick stone or solid concrete partitions reduce it. If your space exceeds 500 m², or has multiple separated rooms across two floors, you'll need two C500 units or a custom DAS design. The 365-day refund covers a wrong-size purchase.

The 10 dBi directional Yagi is a deliberate flagship upgrade. On a large premises you typically know which direction the nearest mast is (check Ofcom's Coverage Checker), and a Yagi concentrates gain in that direction — pulling in weaker distant signal that an 8 dBi omni would miss. The trade-off is you must aim it within ±15° of the mast; the included compass guide makes this straightforward. If you have masts in multiple directions or can't identify the donor, the C250's omni is more forgiving.

The 30+ rating means the C500 can serve 30+ active 4G sessions at once without throttling. In a 20-person office, that covers every staff phone plus guest phones, POS terminals, tablets and mobile hotspots. The advanced AGC dynamically allocates gain so a single heavy video call doesn't starve the rest of the team. For 40+ users or a call-centre environment, you'd want two C500 units or a DAS.

It depends on the total floor area. If the three floors add up to under 500 m² and the indoor panel antenna is mounted centrally (e.g. on the ground-floor ceiling or first-floor landing), yes — the 23 dBm output pushes signal vertically through floorboards better than 20 dBm units. If the house is over 500 m², or has thick concrete separating floors, you may need a second indoor panel antenna on a splitter, or a second C500 unit upstairs.

No. The C500 includes advanced digital AGC (Automatic Gain Control) that continuously adjusts gain to the minimum needed, capped at the Ofcom-legal 23 dBm EIRP. As long as you separate the outdoor Yagi and indoor panel by at least 5–10 metres (or a solid wall between them), the AGC prevents oscillation. Boosters without AGC — which are illegal in the UK — are the ones that cause interference. The C500 is Ofcom licence-exempt precisely because it self-regulates.

The 10 dBi Yagi effectively extends the usable donor range by roughly 30–40% compared to an 8 dBi omni. In rural UK, where the nearest Band 20 mast is 3–6 km away, the Yagi will lock onto a usable 1–2 bar signal where an omni might show zero. Beyond 8–10 km with hilly terrain, even a Yagi may struggle — in that case, try mounting it higher on a pole or chimney. If there's still no donor signal, no booster can help.

15 m reaches most exterior walls to the indoor unit inside a typical house. If your Yagi mounts on a chimney, far gable, or you're running the booster in a detached garage/outbuilding, you'll likely need the 20 m / 30 m / 40 m / 50 m upgrade cable (available at checkout). Longer cables lose signal, so we recommend staying under 30 m for the C500; beyond that, the 75 dB gain compensates but the noise floor rises slightly.

Yes — that's exactly what it's designed for. The 23 dBm output and 30+ user rating cover a typical 200–500 m² retail floor, driving signal through shopfront glass and solid back walls. Staff phones, customer 4G, card terminals and Wi-Fi calling all improve. For chain stores, multi-floor retail or 50+ staff, you'd deploy multiple C500 units or a DAS. The Ofcom licence-exempt rating means no business radio licence paperwork.

The C500 comes with a 365-day money-back guarantee — if it doesn't improve your signal within one year, return it by mail for a full refund (free return). You also get lifetime UK-based technical support by email and chat. Free UK delivery takes 10–15 working days with 1–2 day handling. The unit is built to CE/Ofcom standards and the power supply has UK 3-pin safety certification.