CoreBox i5-8259U 16GB Memory Timings

Hello. I rescently bought a used CoreBox i5-8259U 16GB + 512GB. I will be using it for some light media tasks, etc. Everything is great, except the memory tests very slow and single channel. Odd. The BIOS has an incredible array of memory Over clocking options. Does anyone know of stable settings to reach at least 1866 or even 2133? Currently, on defaults, it benches as 1330 MT/s

Thanky you for any help!