No cellular service and Reset Network Settings doesn't work

iPhone 7 with OS 14.0.1. Won't connect to cellular network since update. Cellular settings just says "Error"- if I enter that screen instead of seeing settings like cellular data etc. it just says an update is required (but again, I just updated it). Yes, I have tried toggling airplane mode, powering off/on the phone, hard restarting the phone, taking out and then replacing the SIM card, and every combination and permutation of these operations. Yes, I have also tried to "Reset Network Settings" but it just hangs unresponsive for about 30 seconds on that screen- no reset actually occurs.

Anyone?