iPhone 18 Pro notifications delayed on cellular data

1. Sometimes, a simple restart can resolve temporary software glitches. Turn off your iPhone, wait for a few seconds, and then turn it back on.
   1. Restart the device. That's it.
   2. Still not solved --> Force restart iPhone - Apple Support
2. If you're using a VPN, disable it and check if the error goes away. Go to Settings > General > VPN & Device Management and turn off any active VPNs. Disabling a VPN only from the iPhone settings may not completely turn it off. To fully disable it, you need to switch it off from the VPN service provider’s app or remove the configuration profile they installed. Only then is the VPN truly off, which can help if it’s causing issues with cellular or Wi-Fi connectivity.

If notifications are delayed only when your iPhone is connected to a cellular network, but arrive promptly when connected to Wi-Fi, this suggests that the issue may not be with the iPhone itself. Instead, it could be related to your cellular network, carrier, or SIM card.

As a first troubleshooting step, try removing the SIM card and reinserting it. This may help re-establish the connection with your cellular network.

You can also try the following:

• Toggle Airplane Mode ON, wait for about 15 seconds, and then turn it OFF.
• Restart your iPhone.
• Check whether the issue persists in different locations, as it could be related to cellular network coverage or congestion.
• Contact your cellular carrier if the problem continues, as they may need to investigate network-related issues.

If notifications consistently arrive on time over Wi-Fi but are delayed on cellular data, that is a useful indication that the problem may be related to the cellular connection rather than an iOS notification setting. However, it does not conclusively rule out an iPhone or app-related issue.

All notifications of from a specific app or service?