Hi uzmaq,
We appreciate you reaching out to us. We understand that you are experiencing Wi-Fi connectivity issues. Also, your device is freezing.
We’d like to gather additional details that may help us be in a better position to assist you.
Have you had the chance to make sure that your available storage is not extremely low?
Do you have accessories that are connected or paired with your iPhone 6? If yes, does it help if you disconnect or unpair your accessory?
It looks like you came from the article below. Have you had the chance to try all the steps in that article?
If your iPhone, iPad, or iPod touch won't connect to a Wi-Fi network
In the meantime, the steps in the article below may help.
If your iPhone won't turn on or is frozen
Also, we recommend that you check your device's battery health.
A degraded battery may cause performance-related issues.
iPhone Battery and Performance
Take care!