LTE but no WiFi on iPhone 11

Connect to Wi-Fi on your iPhone, iPad, or iPod touch

1. From your Home screen, go to Settings > Wi-Fi.
2. Turn on Wi-Fi. Your device will automatically search for available Wi-Fi networks.
3. Tap the name of the Wi-Fi network that you want to join.

Connect to Wi-Fi on your iPhone, iPad, or iPod touch

Check your WiFi Router / Modem for --> Recommended settings for Wi-Fi routers and access points ...

This may help you -> About the LTE options on your iPhone - Apple Support (IN)