Hi there. I'm sorry you're experiencing issues.
That said, it sounds like all of those issues aren't really related to GrapheneOS.
I would recommend following everything in https://grapheneos.org/usage#carrier-functionality as a first step, but if that doesn't help, this is quite likely an issue that would occur anywhere. Issues like that crop up sometimes and are usually fixed upstream. We're getting the QPR3 update soon, which should hopefully address any issues you're facing, though that's not certain.