Round trip
Ping is the time an input takes to reach the Diablo IV server plus the time the reply takes to come back.

Setting up GamesTC for Diablo IV takes a few minutes: install the app on Windows, sign in, pick the game and connect before you start playing. The app suggests a route and shows your ping so you can check it.
GamesTC Network
7 associated city(ies):
Game traffic only
Only the game goes through the tunnel on low-latency routes. Everything else stays on your normal connection.
GamesTC Detailed Smart Route
Connection quick guide
When your inputs feel late, it is almost always the round trip to the Diablo IV server, not your PC. That delay adds up from distance, your ISP's routing and queues at every router along the way. GamesTC works on the routing part.
Ping is the time an input takes to reach the Diablo IV server plus the time the reply takes to come back.
Fewer detours mean fewer milliseconds between your click and what happens on screen.
Keeping the same ping all match long matters more than hitting the lowest number once.
A path chosen to cut packet loss to the Diablo IV server.
Built to take as little CPU and memory as possible.
Uses separate entry and exit nodes only when measurements show a real gain.