what’s wrong with my iphone?

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

Connecting to Wifi is the first part and then getting connected to the Internet is the second

1. If you connect to Wifi, doesn't necessarily mean you are connected to the internet. If you are not connected to wifi could be a problem with iPhone settings or Router/Modem Settings
2. If you are not connected to the internet is the sole issue of Router / Modem Settings. Contact your ISP immediately

For your Internet connection.

• Over Cellular: contact your Carrier (Cellular Service Provider). The agency who issued the SIM to you
• Over WiFI: Contact your ISP (Internet Service Provider), the agency who provided the Internet Service on your Modem/Router to you

However --> Connect iPhone to the Internet - Apple Support

Cellular data is a feature of your cellular network provider. Do you see the name of the provider in the top bar? do you see “bars” showing signal strength? If not contact your provider. If you do see the provider’s name and signal bars go to Settings/Cellular and turn it on, also make sure it is on for each of your apps.

Social media apps do need an internet connection when using them. I don't know how the recent posts would update if you're not connected to the internet. And internet can either come from the Wi-Fi or cellaular data.

Please make sure that your ellular plan includes cellular data. Some of these plans have data limits. If you've already used up your cellular data allowance, you might be asked to connect to Wi-Fi instead. For that one, you can ask your carrier for further help

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...