Unreal will disconnect your card if.
1- Not enought Vram.
2- Overclocking
3- Using old driver or not up to date.
Unreal always disconnected my card, I was starting to go crazy and never overclocked my card. I’m not a computer parts geek so… I bought the best card of the moment but after some research I bought an Asus RTX 3070ti… I hadn’t realized that on the box of my card there was written “OC” it means the GPU is overclocked out of the box… i felt silly… so i download the Asus GPU Tweeker and lower the frequency to 1500, “normal state” this solves the problem for me, it also make my GPU quieter… it still adds this error sometimes when i work with the big world and i load all the proxies from my world partition but it’s related to the vram and not to the GPU frequency anymore.
I hope it help some of you.