Apple Watch and iphone

Check your watch has not got into Silent mode because that seems to be a frequent problem. Swipe up for Control Center and make sure the bell is not red.

Next I would start by rebooting both devices (forced reset).

How to restart your Apple Watch - Apple Support

If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support

If that doesn’t solve the problem check your settings in the Watch app, Notifications, Phone.

Notifications on your Apple Watch - Apple Support

Actually you can. Both my iPhone and Watch ring at the same time (with different Ringtones). To enable this....go to your Apple Watch App on your iPhone and scroll down to "Phone"...next Tap on it and check "Mirror my iPhone"...I also have "Sound" and "Haptic" On.

Yes all my devices connected ring! It’s like circus!