The speed of wifi is slow on only my device.

Hello VaishakReddy_,

It sounds like the internet on your iPhone is slow and other devices work as expected. 

Here are some troubleshooting steps and resources that can help:

• Follow the steps in If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network as it has steps relevant to slow Wi-Fi. 

• Update your iPhone, iPad, or iPod touch.

• Test it in different apps. 

• Test different Wi-Fi networks. 

• Check for wireless interference Resolve Wi-Fi and Bluetooth issues caused by wireless interference.

• As it relates to your network, check for any of the following, uninstall it and try again. (Note: if you don't have any, you may not see these options in Settings.)
  • Security apps.
  • Private browsing/optimization apps.
  • Settings > Safari > Content Blockers.
  • VPN apps and Settings > General > VPN (even if it says Not Connected). 
  • Profiles related to your network in Settings > General > Profile. 

Hope this information helps. 

Have a good day.