Last post was closed with zero answers for some reason. Thanks mods 
I’m having an issue where when I try to open the game it says its launching then does nothing and the button goes back to play. I resolved this the other day by reinstalling battlenet but to do that had to use a VPN as the install was hanging at around 35%. I have now discovered that using a VPN to launch WoW seems to work. Any ideas why this would be happening and what i can do to fix
Using VPN’s is not supported, and actually I believe it to be against the terms of service.
There have been reports on these forums, of players who were banned for the use of VPN’s. However its important to keep in mind, thats only what the players claimed they were banned for. Blizzard never publicly disclose why they ban a player, except to that player.
VPNs are not against the EULA per se, but there have been a few threads where it seems like people have been banned for using a VPN to circumvent sanctions placed on their country.
Also sometimes using a VPN may result in a wrongful ban because it may look like they’re using it to break the EULA (for example an instant change in location might seem like account sharing).
As for OP I suggest you troubleshoot your connection first.