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
Flash your card and you get 30mh/s or more, and if you not want to flash, use amdtweak. By the way, shown hashrate is not interesting, the real pool hashrate is more interesting and here are lolminer and teamred better than all other AMD miners.