Today Server1910 installed when Ubuntu, re-tried several times in the card
curtin command in-target
View detailed information is found stuck in a web address, estimated to be installed before the connection to the server is updated, but the connection with the unreasonable part of the server, has led to retry the connection, stuck.
So I modified the installation after the restart mirroring source address of NetEase mirrored at the beginning:
http://mirrors.163.com/ubuntu/
Then the installation can proceed smoothly.