I use a Timredminer, lolminer gives a smaller hashrate
RX570 8G without overclocking gives 24-25 megahashes, can you try the operating system on Linux?
Getting 24 - 25 megahash on 8gb variant of rx570 isn't good, atleast the graphic card should be outputting 30mh/s, it's better if OP can change OS, windows OS sometimes can drag down mining hashrate for different reasons but on Linux it's not same, Linux OS is smaller and lighter