Hi there, kindly follow the below steps:
1 . Kindly check if your device is on the latest software version. The latest software version is Version WW-17.1810.2007.165.
2 . Check your device WiFi connectivity on other network.
3 . Check if the same works on mobile data.
4 . For performance check if there is sufficient RAM available before you start the game
5 . Restart the device once before starting game.
6 . If still the issue persists nothing factory reset once to refresh your phone after taking full backup of the device:
https://www.asus.com/support/FAQ/1006346/