Are you having issues logging into Ragnarok Origin via Mobile Data? Please give the below options a try!
Go to the Settings > Connections > Mobile Networks > Access Point Names, on your mobile device. Make sure to click on Existing Entries and remember the settings (writing them down or taking a screenshot are easy ways).
Return to Access Point Names and click on Add. The name doesn't matter so name it whatever you would like. Input the settings that you noted previously but change APN Protocol and APN Roaming Protocol to IPv4/IPv6. Then just hit Save.
Your service will then likely disconnect and reconnect. After which you should be able to access Ragnarok Origin with no issues on Mobile Data!