I have not used it personally but I have seen some others recommend it. It seems legit to me but no personal experience. I used one called "gamepath" for connecting to asian servers, not even sure if that one is still around.
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Here is a FAQ on their site how to use it for a "custom game"
https://wtfast.zendesk.com/entries/25122932-What-if-my-game-is-not-on-the-Supported-Games-List-
