rosdep update problem of ros

Every time I install ros to this point, I get desperate. Sometimes the hotspots work and sometimes they don’t work. It’s a network problem.
https://www.ipaddress.com/ Open the following web page

Enter raw.githubusercontent.com to query the address

and then

sudo gedit /etc/hosts

At the end, it must be the end position, join

199.232.96.133 raw.githubusercontent.com

solve