The connection issues when on mobile data might be caused by some internet carriers using the IPv6 protocol as default. We kindly recommend you to change it to IPv4 or IPv4/IPv6.
Go Settings -> Connections -> Mobile networks -> Access Point Names. Select your mobile operator then scroll down to APN protocol and select it.
Then select IPv4 or IPv4/IPv6.
If you still experience any issues, please let us know on madfingergames.com/help, thank you.