Your DS slot might be dirty. Clean the slot with compressed air. Alternatively, the R4 cartridge’s contacts may be oxidized – rub them gently with a pencil eraser.
No. The SDHC standard only supports up to 32GB. Anything larger requires SDXC, which the R4’s controller cannot address. Stick to 32GB max. r4 sdhc dual core 2016 firmware download
Why 2016? That year marked a significant firmware update that improved game compatibility (notably for Pokémon Black/White 2 and later DS titles), fixed SDHC card recognition errors, and implemented anti-piracy bypasses. In this guide, we’ll cover everything you need to know: where to find the firmware, how to install it, common error fixes, and safety tips to avoid bricks or malware. Your DS slot might be dirty
(Always scan any downloaded file with Windows Defender or Malwarebytes before opening.) Stick to 32GB max