Multipass uses the native “Hyper-V” hypervisor on Windows, along with the “Default Switch” created for it. That, in turn, uses the “Internet Sharing” functionality, providing DHCP (IP addresses) and DNS (domain name resolution) to the instances.
Default Switch going awry
Unfortunately the Default Switch is known to be quirky and Windows updates often put it in a weird state. This may result in new instances failing to launch, and existing ones timing out to start.
The broken state also persists over reboots. The one approach that has helped is removing the network sharing from the default switch and rebooting:
PS> Get-HNSNetwork | ? Name -Like "Default Switch" | Remove-HNSNetwork PS> Restart-Computer
Hyper-V will recreate it on next boot.
Stale Internet Connection Sharing lease
Another reason for instance timeouts may be that a “stale” IP address for a particular instance name is stored in the
Internet Connection Sharing hosts file.
Using Administrator privileges, edit
C:\WINDOWS\System32\drivers\etc\hosts.ics and look for any entries that have your instance name in it. If there is more than 1 entry, remove any of them except for the first listed. Save the file and try again.