I'm trying to check for system updates but it just hangs "checking" and nothing happens.
Last update check was 2 days ago.
You could try and go to your apps in settings, make sure you show system, find the "update launcher" and clean the storage
If that doesn't help, then it might get resolved by downloading the FW manually via https://www.asus.com/Phone/ZenFone-6-ZS630KL/HelpDesk_BIOS/
All you have to do is to place the downloaded file in the root directory of your phone and it should find the update right away. If not, try a restart.
There will be a .119 FW available soon