Why do I have different ping o

Why do I have different ping on the same server in Dota 2 (Asia, Singapore) ?
Sometimes 104, sometimes 120.
In the game in the server selection window it shows one ping but into the game it is another ping. When I play using my ISP route, ping is constant every game.

RTT updating process may could be delayed depending
on how RTT calculation server is under load. That means it’s estimating,
not actual RTTs.

mudfish.net/docs/en/faq/nodes.html#how-do-i-get-the-updated-routing-paths.

So these behaviors occur showing different RTT values in Mudfish
dashboard and in-game measurement.

The advanced mode possibly cause increases
instability

of connections.