We believe that the IPv6 communication is the issue here. We tried to disable this type of communication on your friend’s Roon account, can you please ensure that they restart RoonServer twice and then check to see if they are still having issues? Do let us know!
Glad to hear that it worked for your friend! The reboot twice is needed for Roon to download new settings from our servers. We are looking into a permanent fix for this issue but in the meantime we can leave the fix active for your friend.