Cannot set up the CUDA network repository

Hi, everyone. I’ve got into trouble installing CUDA on WSL2 when following the official guide. I’m currently using Ubuntu20.04-LTS. However, the following “404 Not Found” error occured:

I tried to change the source in my source.list.d/cuda.list into “ /”, but it still didn’t work.
I’m confused because generally speaking, “404 Not Found” indicates that a source is no longer used or the repository has been migrated, but both the 1804 and 2004 repo can still be accessed via my browser…(for example, by directly paste the address Index of /compute/cuda/repos/ubuntu2004/x86_64)Does anyone encounter similar problems?