Personally, I have the same symptoms on iPhone 6s and iPhone 11. And immediately on two operators: on Yota, which on Tele2. The iPhone sees the network, there is a signal, calls go through, but the Internet does not load a single site until the very reboot. A friend has a similar problem with MTS with the iPhone 11 Pro.
You can fix the error only by rebooting the smartphone. Input and output from Airplane mode do not help.
Do you do the same?