Hey there JirmWarfare,
To help with setting up cellular on your Apple Watch, look over the details below to ensure everything is configured properly:
"Before you start
- Make sure that you have the latest software on your iPhone and your Apple Watch.
- Check for updates to your carrier settings.
- Make sure that you have an eligible cellular service plan with a supported carrier. Your iPhone and Apple Watch must use the same carrier,* and you must be within your carrier's network when you set up cellular on your watch.
- If you have an enterprise or corporate cellular service plan, check with your company or carrier to see if they support this feature. Pre-paid accounts and some older accounts aren’t currently supported. To make sure that your account is eligible, contact your carrier.
* An Apple Watch that you set up for a family member can use a different carrier than your iPhone uses."
To continue with getting cellular set up, use the next set of steps:
"You can activate cellular when you first set up your Apple Watch, or when you set up a watch for a family member. During setup, look for the option to set up cellular, then follow the onscreen steps.
You can also set up cellular later from the Apple Watch app:
- On your iPhone, open the Apple Watch app.
- Tap the My Watch tab, then tap Cellular.
- Tap Set Up Cellular.
- Follow the instructions for your carrier. You might need to contact your carrier for help."
You'll find the details above in this support article:
Set up cellular on Apple Watch - Apple Support
Take care!