http://precious.htb/ cant download pdf, loading loading and loading, help!!
Hey there! 
You can always look for help in the official machine thread
So about your problem, have you added the precious.htb address to your /etc/hosts file?
Also consider that the machines don’t have connection to external websites (I mean that in this case you can’t convert to pdf sites like google.com etc because the machine would not be able to connect to that website)
You could try to reset the machine (sometimes it helps as other players may break something before you even got started!)
Try checking your VPN connection and consider switching from udp to tcp as it makes the connection a bit more stable.
PM me if the problem still persists