Only 30m Range on telemetry

I’m only getting 30m range on my Telemetry. Using 500 mW x-rock from Banggood. 100% signal at 5m but then loosing fast. Power at 20 db. 500mW should be 27 dB but can’t be adjusted in MP. At some point I think I have updated to standard firmware which was a misstake. Anyone have any suggestions or can share firmware?