It would not immediately be obvious but would have catastrophic knock on effects.

For day to day living the first thing people would notice is their home WiFi stops working and their mobile phone doesn't work at all (calls, mobile data, WiFi). And - as most countries still do it - terrestrial TV broadcasts would suddenly stop (possibly affects rural areas more, many homes in urban centres use cable but obviously this depends on your country). Radio would stop working obviously.

Military-wise it would probably mean immediately going to a state of high alert as a simultaneous loss of communication to many places would be interpreted as an attack that needs immediately investigating. While the military network is resilient and has non-radio ways of communicating it's not expecting to switch to this in an instant and there would be great paranoia about what's actually going on.

All planes would cease being able to communicate with ATC which would effectively ground the entire civilian air space. Instrument landing systems (runway radio beacons) would stop working so all landings would be manual, if the weather was bad pilots would have to divert without being able to check availability with anyone. Clearing the air without radio is a mammoth task and there would almost certainly be accidents as multiple planes try to approach the same run ways, or land on ones that are occupied, or run out of fuel seeing congested runways below and nowhere to go.

Urban rail transit would grind to a halt with drivers losing comms with signal switch stations. Some have non radio alternatives but with every walkie talkie ceasing to work this may not be enough. The network (like the tube and the metro) would halt and slowly manage an evacuation.

There would be general chaos trying to get to work (inc hospitals and other key workers) as RFID security passes stop working and everyone has to be validated manually.

Overall, apart from with airlines, I think the first day it would be inconvenient but not lethal. But then what would follow would be a lot of urban society being unable to function safely. Delivery via air would grind to a halt. Any location requiring security would lock down as security staff would have no way of communicating out of sight unless the place still had wired phones. Governments would immediately be assessing how long their national stockpiles would last without air freight. Possibly highways would get nationalised under emergency government control to prioritise road freight.

China would possibly invade Taiwan. It would be disastrous attempting an invasion without radio but they would probably have calculated that it affect the Americans worse.