Multipass is a very useful tools to create Ubuntu VM instance. It will provides a CLI to launch and manage the Linux instances. The downloading of a cloud image is also automatically, and a VM can be up and running within minutes.

But in my case, I tried multipass 1.1.0 to quick launch an instance, but it failed with a Network timeout error.

$ multipass version
 multipass  1.1.0
 multipassd 1.1.0

$ multipass launch
launch failed: failed to download from '': Network timeout

I checked this link with wget and has no issue, so I assumpt the download time of the image may too long to some timeout value in multipass. Can we download it manually and start the instance by it? Sure we can. You can download the images and pass the image path as a parameter.

$ multipass launch file:///home/wshi/Downloads/ubuntu-18.04-server-cloudimg-amd64.img
Launched: lucrative-eelpout 

One more thing about the download time in Japan. Using seems slow to me. So I switched to the mirror of Toyama Univ. It's 10 times faster than the origin one, hope this can help you.